1    
Acker, Richard H. 1994. The Quiet (Energy) Revolution: Analyzing the Dissemination of Photovoltaic Systems in Kenya. M.P.A.
Thesis, Princeton University, 107 pages.

The widespread introduction and adoption of renewable energy technologies remains high on virtually every national development
policy agenda; renewable energies can assist national energy autonomy, decentralize resource management, promote environmental
conservation, and serve as a means to reduce global warming. The track-record of efforts to turn this noble ideology into successful
technology transfer and dissemination, however, remains very mixed. It is a story of a few successes amid many failures. Here we
document and examine the diffusion of small-scale photovoltaic (PV) systems in Kenya. At the same time that integrated energy plans
and top-down models championing renewable energy futures are becoming increasingly common, a new power base, divorced from
these grand schemes, has begun to emerge. Over the past decade, some 20,000 to 40,000 small PV systems, essentially all privately
financed, have been installed in Kenya. Many valuable lessons for renewable energy research can be found here. The Kenyan case
richly illustrates the dramatic role that actors on every scale, from grass-roots to international, can have in accelerating -- or when
mismanaged, impeding -- technology transfer and the elevation of renewable energy systems from niche applications to a prominent
role in household empowerment, and decentralized and sustainable development initiatives.

Major Professor(s): Kammen, Daniel M.
Department: Woodrow Wilson School of Public and International Affairs
Principal Investigator(s): Kammen, Daniel M.
Program Area: National Institute for Global Environmental Change (NIGEC)

KEYWORDS: AFRICA, POLICY, SOLAR ENERGY


2    
Ackerman, Andrew S. 1994. A Numerical Modeling Study of the Effects of Variations in Aerosol Concentrations on Stratiform
Clouds in the Marine Boundary Layer. Ph.D. Dissertation, University of Washington, 230 pages.

Marine stratiform clouds play an important role in the global radiative heat budget of the Earth because they overlie about a third of
the oceans and they reflect much more sunlight than the ocean surface. The reflectivity of these clouds depends in part on the
concentrations of cloud condensation nuclei (CCN) on which cloud droplets form. Here a numerical model is used to investigate
interactions between aerosol and cloud microphysics, radiative transfer, and turbulent mixing in the stratiform cloud-topped marine
boundary layer. Results from model simulations are found to be in general agreement with airborne measurements of marine
stratocumulus clouds. However, the model underpredicts the concentrations of small cloud droplets in the lower region of the cloud
layer. This is consistent with the lack of a peak supersaturation near cloud base in the model results, which is attributable to horizontal
averaging in the model. The model simulations indicate that equilibrium CCN concentrations are sensitive to their formation rate. The
times required to reach equilibrium were found to increase with increasing CCN concentration, suggesting that cloud layers can
maintain high CCN concentrations long after the supply of CCN is reduced. The results of the model show cloud albedo to be more
sensitive to cloud droplet concentrations than under the assumptions that cloud water is fixed and unactivated haze particles are
ignored. Increased droplet concentrations generally (but not always) produce increased cloud water due to reduced drizzle. The
number of haze particles increases with droplet concentrations due to decreased peak supersaturations in the cloud. The model
simulations show that when droplet collisions reduce droplet concentrations to extremely low values, a cloud layer can become so
optically thin that cloud-top radiative cooling is unable to drive vertical mixing. The stratocumulus-topped marine boundary layer can
then collapse to a shallow fog layer over the course of a day or more. The model was also used to investigate long-lived, linear regions
of enhanced cloud reflectivity that appear in satellite imagery downwind of ships. We have found that injections of CCN, which are
present in ship exhaust, can account for many of the observed properties of ship tracks. Ship tracks are classified as Type 1, which are
observed in visible satellite imagery, and Type 2, which are more common and are observed in near-infrared imagery. The distinction
between the two types is attributed to differences in ambient concentrations of CCN that cause variations in turbulent mixing in the
marine boundary layer, through the effect of cloud droplet concentrations on cloud-top longwave radiative cooling.

Major Professor(s): Hobbs, Peter V.
Department: Atmospheric Sciences
Principal Investigator(s): Toon, Owen B., and Douglas L. Westphal
Program Area: Atmospheric Radiation Measurement (ARM)

KEYWORDS: AEROSOLS, BOUNDARY LAYER, CLOUDS, CONDENSATION, MARINE ENVIRONMENT, MICROPHYSICS,
PARTICULATES, REFLECTANCE


3    
Ahmed, Faisal Elgasim. 1992. Heat Injury to Reproductive Development in Cowpea (Vigna unguiculata (L.) Walp.) Under
Ambient and Elevated Carbon Dioxide Concentrations. Ph.D. Dissertation, University of California at Riverside, 100 pages.

Physiological basis of heat injury during reproductive development was studied using contrasting cowpea (Vigna unguiculata L.
Walp.) genotypes subjected to different night temperatures and light qualities under ambient and elevated levels of CO2 in growth
chambers. The objectives were to: determine the stages of reproductive development when damage due to heat stress occurs; test
whether specific tissues or developmental processes are damaged during the periods of sensitivity to heat; evaluate the interactive
effects of temperature and light quality during the day on floral development; and test for possible associations between carbohydrate
limitations and sensitivity to heat during reproductive development. High night temperature during the vegetative and early
reproductive states causes complete suppression of floral buds on the main stem. Transfer experiments demonstrated that plants were
not sensitive to heat at a particular stage of development but that the duration of heat experience is critical for floral bud development.
Two weeks or more of continuous or interrupted heat caused complete suppression of all floral buds suggesting that the heat stress
effect was cumulative over time. The degree to which high night temperature suppressed floral bud development depended on the
R/FR ratio during the day and values of 1.3 to 1.6 were required to elicit the same responses as occur under natural sunlight. High
night temperature during anther development causes male-sterility and results in no pod set due to low pollen viability and anther
indehiscence. The stage of floral development most sensitive to heat occurred nine to seven days before anthesis. During this period,
premature degeneration of the tapetal tissue and lack of endothecial formation were detected in heat stressed plants. These two
abnormalities may be responsible for the low pollen viability, low anther dehiscence and low pod set observed under heat stress. Under
high night temperature, different heat sensitive genotypes either produced no flowers or set no pods at either ambient or elevated CO2,
whereas the heat tolerant genotype abundantly set pods. The high pod set of the heat tolerant genotype was associated with higher
levels of sugars in peduncles compared with the heat sensitive genotypes. Elevated CO2 resulted in higher overall carbohydrate levels
in heat sensitive genotypes but sugar levels in peduncles were not improved indicating that heat stress affects assimilate demand to a
greater extent than assimilate supply. It is hypothesized that sensitivity to heat during reproductive development is due to
developmental lesions that are not overcome by enhanced carbohydrate supplies through CO2 enrichment. A heat tolerant genotype
was most responsive to CO2 enrichment, with respect to pod production, under either high or intermediate temperatures.

Major Professor(s): Hall, Anthony E.
Department: Botany and Plant Sciences
Principal Investigator(s): Hall, Anthony E.
Program Area: National Institute for Global Environmental Change (NIGEC)

KEYWORDS: CARBON DIOXIDE, FERTILIZATION, GROWTH AND DEVELOPMENT, HEAT STRESS, REPRODUCTION,
VEGETATION


4    
Akkarappuram, Anto Francis. 1988. Air-Sea Exchange Processes off the Carolinas During the 1986 East Coast Winter Storms -
GALE (Genesis of Atlantic Lows Experiment). M.S. Thesis, North Carolina State University, 105 pages.

GALE, a national and multi-institutional project to study the physical mechanisms causing the formation and development of winter
storms, was centered around the eastern Carolinas along the east coast of the United States from 15 January to 15 March, 1986. Data
from six moored buoys in the coastal waters off the Carolinas and two research vessels mostly stationed at the western boundary of
the Gulf Stream (GS) were used to study air-sea interaction processes. Data selection for the period of 20 January to 13 February,
1986 included several cases of cold air outbreaks, cold front passages, coastal frontogenesis, and offshore cyclogenesis. Prevalence of
non-neutral conditions during the entire time period of GALE necessitated the selection of an appropriate method to account for the
diabatic effects for computing the surface fluxes from the routine surface GALE data. An Iterative Bulk Aerodynamic Method
(IBAM) is compared with the eddy correlation- and energy dissipation method to obtain surface fluxes of momentum and heat during
the non-neutral boundary layer conditions and high winds ( 22 ms-1). After the intercomparisons of IBAMs, the IBAM of Liu, et al.
(1979) was selected as a good indirect bulk method to use with the GALE data sets. Fluxes of momentum and heat from the
mesoscale network of buoys and ships show significant temporal- and spatial variations in the coastal waters and along the western
boundary of the GS with the south to north and cross-stream gradients. Spatial and temporal variations of these fluxes depend on the
formation, location, intensity, and path of large-scale disturbances. During GALE, the highest fluxes, as measured from research
vessels and buoys, occurred off the coast of South Carolina where high wind speeds and air-sea temperature differences were recorded
frequently. For example, a momentum flux of 1.03 NM-2 and a total heat flux of 1243 WM-2 with an air-sea temperature difference of
about -22øC in the vicinity of the highly baroclinic GS front were observed in this area during the offshore cyclogenesis with cold air
outbreak on 27 January/ at 0900 UTC. A salient feature of the spatial variation across the western boundary of the GS front is the
prevailing accelerating effect that causes large deviations in the surface fluxes. Time series data for the depth of Oceanic Mixed Layer
(OML) from a stationary location during 26/0000 to 27 January/1100 UTC show the response of the depth of OML with a lag of
about two hours to the modulations of surface fluxes induced by the synoptic-/mesoscale atmospheric disturbances. The range of
variations of OML depth is from 50 to 76 m when the variations of momentum, sensible heat, and latent heat are from 0.15 to 1.03
NM-2, 24 to 367 WM-2, and 214 to 874 WM-2 respectively. OML observations are far less than those obtained using one-dimensional
models and the comparison shows that the models do not work well at the western boundary of the GS front probably because of
strong horizontal advection.

Major Professor(s): Raman, Sethu
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Pietrafesa, Leonard J.
Program Area: Marine Transport

KEYWORDS: ATMOSPHERE, CIRCULATION, CLIMATE, COASTAL ENVIRONMENT, HEAT FLUX, MOMENTUM, OCEANS,
SPATIAL DISTRIBUTION, STORMS, TEMPORAL DISTRIBUTION


5    
Alliss, Randall Jamil. 1992. The Utilization of SSMI/I Data in the Analysis of Tropical and Extra-Tropical Cyclones. M.S. Thesis,
North Carolina State University, 143 pages.

Recently, remote sensing of tropical and extra-tropical storms has been enhanced via data from the Special Sensor Microwave/Imager
(SSM/I) launched by the Defense Meteorological Satellite Program (DMSP) in June 1987. Data obtained from SSM/I was analyzed
and used to infer important meteorological parameters of Hurricanes Hugo (1989) and Florence (1988) as well as a mid-latitude
cyclone which developed during Intensive Observational Period (IOP)-4 of the Experiment on Rapidly Intensifying Cyclones over the
Atlantic (ERICA). These parameters include rainfall rates, integrated water vapor, marine surface wind speeds and 85 Gigahertz
brightness temperatures used for center fixing the tropical cyclones. In this study, the utility of the SSM/I as a supplemental source of
data in tropical and extra-tropical cyclones is evaluated. Results indicate that increases in SSM/I derived total latent heat release and
increases in heavier rainfall rates near the center are associated with the intensification of both Hugo and Florence. SSM/I winds give a
good description of the surface wind field of both Florence and the IOP-4 storm, outside areas of deep convection. SSM/I integrated
water vapor is found to be particularly useful in locating the surface fronts associated with the IOP-4 cyclone. In addition, storm
structure characteristics inferred from SSM/I of the ERICA IOP-4 storm compare well with the numerical results produced by the
Naval Research Laboratory mesoscale model. Because SSM/I parameters were useful in observing the structure of these storms and
compared well with in situ observations and model simulations, the applications described herein could be valuable in augmenting
current analysis techniques of tropical and extra-tropical cyclones.

Major Professor(s): Raman, Sethu
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Raman, Sethu
Program Area: Atmospheric Radiation Measurement (ARM)

KEYWORDS: CLIMATE, EXTRATROPICS, HEAT FLUX, PRECIPITATION, REMOTE SENSING, STORMS, TROPICS, WATER
VAPOR, WINDS


6    
Angevine, Wayne. 1993. Heat and Momentum Flux Measurements in the Planetary Boundary Layer with a Wind Profiling
Radar/Radio Acoustic Sounding System. Ph.D. Dissertation, University of Colorado, 85 pages.

The planetary or atmospheric boundary layer is the lowest 100-2000 m of the atmosphere, and contains the sources of most energy
and pollutants that affect the entire atmosphere. Boundary layer structure and dynamics are key to understanding, modeling, and
predicting climate, weather and pollution. New and improved techniques for measuring the dynamics of the boundary layer are
needed. Existing methods involving towers, surface measurements, or aircraft have limited flexibility or are expensive. This
dissertation describes methods for measuring heat flux (virtual temperature flux) and momentum flux in convective boundary layers.
The instrument used is the 915 MHz boundary layer radar wind profiler Radio Acoustic Sounding System (profiler/RASS). As the
name suggests, the profiler was developed to make wind measurements, and this work is an expansion of its capabilities. The radio
acoustic sounding system uses the profiler and attachments to measure virtual temperature. Before the profiler/RASS could be used to
make flux measurements, the ability to make simultaneous measurements of wind velocity and temperature had to be developed. A
feasibility study was conducted in Platteville, CO in June 1991 to determine if flux measurements were a practical application of the
profiler, with encouraging results. The Rural Oxidants in the Southern Environment II (ROSE II) experiment in Alabama in June
1992 provided the opportunity to compare flux measurements from the profiler/RASS to those made by a surface sonic anemometer
and an aircraft, The National Center for Atmospheric Research (NCAR) King Air. The results indicate that the profiler/RASS is
capable of making heat flux measurements that compare well with aircraft and surface measurements. The primary limitation on the
precision of the measurements is the sampling uncertainty of the turbulence, a limitation that is the same for any fixed instrument. The
feasibility of making momentum flux measurements needs to be explored further in more favorable conditions. In the course of
analyzing the flux measurements, methods of determining the mixing depth (boundary layer height) and improved data quality control
techniques were developed.

Major Professor(s): Avery, Susan
Department: Electrical and Computer Engineering
Principal Investigator(s): Gage, Ken
Program Area: Atmospheric Radiation Measurement (ARM)

KEYWORDS: BOUNDARY LAYER, HEAT FLUX, MOMENTUM, RADIO ACOUSTIC SOUNDING SYSTEM (RASS),
TURBULENCE, WINDS


7    
Arnosti, Carol. 1983. Structural Characterization and Bacterial Degradation of Marine Carbohydrates. Ph.D. Thesis, Massachusetts
Institute of Technology and Woods Hole Oceanographic Institution, 239 pages.

The goal of this thesis was to develop and apply an integrated chemical and microbial approach to study the effects of chemical
structure on the rates and patterns of carbohydrate degradation by anaerobic marine bacteria. Polysaccharides produced by five species
of marine plankton, Dunaliella tertiolecta, Emiliania huxleyi, Stephanopixis palmeri, a Phaeocystis sp., and Synechococcus
WH7335, were surveyed using one- and two-dimensional nuclear magnetic resonance spectroscopy (NMR). Two carbohydrates from
Synechococcus WH7335 were characterized in detail. Synechococcus produced an à(1,4) glucose polysaccharide with à(1,6)
branches, which probably function as an energy reserve. The nominal molecular weight of the polysaccharide was ÷5000 daltons.
Large quantities of a glycerol-polysaccharide, which was tentatively identified as a teichoic acid similar in structure to teichoic acids
found in cell walls of gram-positive bacteria, were also produced by Synechococcus WH7335. This is the first report of teichoic acids
in cyanobacteria. Enrichment of bacteria from anoxic marine sediments on specific carbohydrate yielded reproducible model systems
with which to study the degradation of chemically well-defined substrates. Headspace gases (CO2, H2, CH4, H2S) were monitored by
gas chromatography, and carbohydrate substrates and intermediates were separated and quantified via gel-permeation chromatography
and high-pressure liquid chromatography. The transfer of carbon from substrates through to end products was followed quantitatively.
Nuclear magnetic resonance spectroscopy was used to check for selective structural alterations (such as preferential cleavage of
specific linkage types or positions) of the substrates. A series of enrichment experiments showed that mixed cultures of marine
bacteria distinguish even between small, very closely-related substrates which do not require extracellular hydrolysis prior to uptake. A
galactose- (1,3)-arabinose dimer was degraded at half the rate of seven other similar disaccharides and three larger oligosaccharides.
A further series of degradation experiments with polysaccharides (pullulan, laminarin) showed that they are degraded by bacteria at
virtually the same rate as structurally related substrates in the molecular weight range of 300-600 daltons. Degradation of the branched
glucan and the teichoic acid-type polysaccharide from Synechococcus WH7335 was also very rapid. The time-course of bacterial
hydrolysis of pullulan was examined with gel permeation chromatography and NMR to provide the first molecular-level evidence in
marine systems of the bacterial extracellular transformation of high molecular weight organic matter to lower molecular weight
organic matter. NMR spectra provided evidence that the pullulan was hydrolyzed by pullulanase, an endo-acting extracellular enzyme
which preferentially hydrolyzes à(1,6) linkages. This is the first experimental evidence of pullulanase activity among marine
mesophilic bacteria. The culture results suggest that enzymatic hydrolysis of macromolecular carbohydrates to transportable pieces is
not the slow step in bacterial degradation of at least some types of polysaccharides. The results from the oligosaccharide experiments
suggest that certain heteropolysaccharides may not be degraded as quickly. Chemical structure can be more important than molecular
weight in determining degradation rates of carbohydrates. Varying rates of organic polymer degradation in anoxic sediments may be
largely determined by the sensitivity of bacterial enzymatic and transport systems to structural features.

Major Professor(s): Repeta, Daniel J.
Department: Joint Program in Oceanography
Principal Investigator(s): Repeta, Daniel J., and Timothy I. Eglinton
Program Area: Marine Transport

KEYWORDS: BACTERIA, CARBOHYDRATES, CARBON CYCLE, DEGRADATION, MARINE ENVIRONMENT, PLANKTON,
SEDIMENTS


8    
Arsky, Natalie. 1994. Prediction of the Generalized Ecotypes with COLA GCM Using Four Different Bioclimatic Schemes. M.S.
Thesis, University of Maryland at College Park, 22 pages.

The problem of interactive coupling of the AGCM to the biospheric model is examined. Four different bioclimatic schemes, which
relate the atmospheric parameters like annual temperature and precipitation to the vegetation distribution, were implemented. The
schemes were applied to two global climate data sets. One represents the result of the COLA (Center for Ocean-Land-Atmosphere
Interactions) model R-15 version simulation of the present-day climate (without coupled ocean). Ten years monthly averages of near-surface temperature, total precipitation, soil wetness, net long-wave radiation and short-wave radiation absorbed at the surface were
used for schemes calculations. Another data set represents climatological temperature and precipitation data (Jaeger data set, NCAR).
The main result is that all four models are able to reproduce the main features of the vegetation distribution. Thus, the schemes can be
used as a first step in coupling of atmospheric GCM with biosphere, e.g. "interactive biosphere". In addition, they can be a useful tool
in interpreting of the GCM results of future and past climates simulations and a diagnostic tool for verification of the model
performance in a simulation of the present-day climate.

Major Professor(s): Baer, Ferdinand
Department: Meteorology
Principal Investigator(s): Baer, Ferdinand
Program Area: Atmospheric Radiation Measurement (ARM)

KEYWORDS: CLIMATE, MODELS, RADIATIVE PROCESSES


9    
Atherton, Cynthia Shaver. 1994. Predicting Tropospheric Ozone and Hydroxyl Radical in a Global, Three-Dimensional, Chemistry,
Transport, and Deposition Model. Ph.D. Dissertation, University of California at Davis, 209 pages.

Two of the most important chemically reactive tropospheric gases are ozone (O3) and the hydroxyl radical (OH). Although ozone in
the stratosphere is a necessary protector against the sun's radiation, tropospheric ozone is actually a pollutant which damages materials
and vegetation, acts as a respiratory irritant, and is a greenhouse gas. One of the two main sources of ozone in the troposphere is
photochemical production. The photochemistry is initiated when hydrocarbons and carbon monoxide (CO) react with nitrogen oxides
(NOx = NO + NO2) in the presence of sunlight. Reaction with the hydroxyl radical, OH, is the main sink for many tropospheric gases.
The hydroxyl radical is highly reactive and has a lifetime on the order of seconds. Its formation is initiated by the photolysis of
tropospheric ozone. Tropospheric chemistry involves a complex, non-linear set of chemical reactions between atmospheric species
that vary substantially in time and space. To model these and other species on a global scale requires the use of a global, three-dimensional chemistry, transport, and deposition (CTD) model. In this work, I developed two such three dimensional CTD models.
The first model incorporated the chemistry necessary to model tropospheric ozone production from the reactions of nitrogen oxides
with carbon monoxide (CO) and methane (CH4). The second also included longer-lived alkane species and the biogenic hydrocarbon
isoprene, which is emitted by growing plants and trees. The models' ability to predict a number of key variables (including the
concentration of O3, OH, and other species) were evaluated. Then, several scenarios were simulated to understand the change in the
chemistry of the troposphere since preindustrial times and the role of anthropogenic NOx on present day conditions.

Major Professor(s): Soong, Su-Tsai
Department: Land, Air & Water Resources
Principal Investigator(s): Penner, Joyce E.
Program Area: Atmospheric Sciences

KEYWORDS: ATMOSPHERE, CARBON MONOXIDE, CHEMISTRY, DEPOSITION, HYDROCARBONS, HYDROXYL
RADICAL, METHANE, MODELS, NITROGEN SPECIES, OZONE, TRANSPORT


10   
Baik, Jong-Jin. 1989. Tropical Cyclone Simulations with the Betts Convective Adjustment Scheme. Ph.D. Dissertation, North
Carolina State University, 159 pages.

A new convective adjustment scheme proposed by Betts (1986) is incorporated into a tropical cyclone model. The convective
parameterization scheme adjusts the local temperature and moisture structures towards the observed quasi-equilibrium
thermodynamic state and includes non-precipitating shallow convection as well as deep convection. The numerical model used for this
study is an axisymmetric, primitive equation, hydrostatic, finite difference model with 15 vertical layers and a horizontal resolution of
20 km. The model domain covers 1000 km and the spectral radiation boundary condition, which uses a different gravity wave speed
for each vertical mode, is implemented in the model. It is shown that the convective scheme is capable of simulating the developing,
rapidly intensifying and mature stages of a tropical cyclone from a weak vortex. During the early developing stage, the latent heat
release is from the convective parameterization, but at the mature stage the latent heat release is mainly due to the grid-scale phase
change. It is demonstrated that the increasing inertial stability and symmetric instability near the radius of the maximum wind in the
lower troposphere can play important roles in the rapid intensification of the storm. For comparison, an experiment is conducted with
the parameterized convection excluded, leaving only the grid-scale condensation and evaporation. The results show that the
development of a tropical cyclone can be modeled with crude grid-scale condensation and evaporation processes for the 20 km
horizontal resolution similar to other studies. However, the storm with the explicit convective latent heat release is considerably less
intense than that with the parameterized convective latent heat release. The sensitivity of the model storm evolution to the convective
adjustment parameters is investigated. These results show that the model storm develops earlier as the adjustment time scale becomes
small and as the stability weight on the moist adiabat in the lower atmosphere is increased. The model storm evolution is very sensitive
to variations in the saturation pressure departure at the lowest model integer level and the storm at the mature stage has a lower central
pressure as the magnitude of the saturation pressure departure is increased. The adjustment parameters affect the grid-scale
precipitation as well as the convective precipitation and the precipitation is especially sensitive to changes in the saturation pressure
departure. Sensitivity of the model to variations in the sea surface temperature, latitude, initial vortex amplitude, initial moisture
distribution and radiation is studied. The results of the numerical simulations are similar to previous studied. Sensitivity studies with
various horizontal resolutions show that the subgrid-scale heating becomes a larger fraction of the total heating as the horizontal grid
size is increased. The role of shallow convection in the tropical cyclone development is investigated. The simulation with both deep
and shallow convection results in earlier development of the storm than that without shallow convection, but the intensity at the
mature stage is similar in both cases. Finally, comparison of the Betts deep convective adjustment scheme with the Kuo convective
parameterization is made. The result shows that the storm with the Kuo scheme intensifies earlier than the storm with the Betts
scheme.

Major Professor(s): Raman, Sethu
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Pietrafesa, Leonard J.
Program Area: Marine Transport

KEYWORDS: CLIMATE, CONDENSATION, CONVECTION, EVAPORATION, MODELS, STORMS, TROPICS


11   
Benkovitz, Carmen M. 1994. Development and Testing of a High-Resolution Model for Tropospheric Sulfate Driven by
Observation-Derived Meteorology. Ph.D. Dissertation, New York University, 265 pages.

A high-resolution three-dimensional Eulerian transport and transformation model has been developed to simulate concentrations of
tropospheric sulfate for specific times and locations; it was applied over the North Atlantic and adjacent continental regions during
October and November, 1986. The model represents emissions of anthropogenic SO2 and sulfate and of biogenic sulfur species,
horizontal and vertical transport, gas-phase oxidation of SO2 and dimethylsulfide, aqueous-phase oxidation of SO2, and wet and dry
deposition of SO2, sulfate, and methanesulfonic acid (MSA). The meteorological driver is the 6-hour output from the forecast model
of the European Centre for Medium-Range Weather Forecasts. Calculated sulfate concentrations and column burdens, examined in
detail for October 15 and October 22 at 6Z, are related to existing weather patterns. These results exhibit rich temporal and spatial
structure; the characteristic (1/e) temporal autocorrelation time for the sulfate column burdens over the central North Atlantic averages
10 hours; 95% of the values were 25 hours or less. The characteristic distance of spatial autocorrelation over this region depends on
direction and averages 1600 km; with 10th percentile value of 400 km and 90th percentile value of 1700 km. Daily average model
sulfate concentrations at the lowest vertical level accurately represent the spatial variability, temporal episodicity, and absolute
magnitudes of surface concentrations measured by monitoring stations in Europe, Canada and Barbados; over 50% of model
concentrations are within a factor of 3 of the observations. Over 50% of weekly model sulfate wet deposition amounts are within a
factor of 3 of observations from US monitoring stations. Over the 34-day period modeled, contributions from anthropogenic emissions
to the sulfate over the mid North Atlantic Ocean ranged from 44 to 66%, contributions from biogenic emissions were between 6 and
12%. Calculated average yields for sulfate (47 to 72%) and MSA (13%), and turnover times for SO2 (2 to 3 days) and sulfate and
MSA (4 to 8 days) are comparable to previous estimates; however, these quantities depend on meteorological conditions and on the
geographic and vertical distributions.

Major Professor(s): Hoffert, Martin I.
Department: Earth System Science
Principal Investigator(s): Schwartz, Stephen E.
Program Area: Atmospheric Sciences

KEYWORDS: EMISSIONS, MODELS, SPATIAL DISTRIBUTION, SULFUR SPECIES, TEMPORAL DISTRIBUTION,
TRANSFORMATION, TRANSPORT


12   
Bermudez, Alejandra Paez. 1982. Carbon Dioxide Enrichment: Its Direct Effects and Its Interaction with Water Stress Relative to
Apical Dominance and Growth of Pea and Tomato Plants. Ph.D. Dissertation, Duke University, 171 pages.

A continued increase in atmospheric carbon dioxide could have a profound effect upon plant growth, resulting in a change in
composition and structure of agricultural and native ecosystems. The objectives of this study using increased atmospheric CO2 were:
1) to determine its effects on apical dominance; 2) to obtain information on changes in growth response for species and cultivars; 3) to
investigate the interacting effect with water stress on plant growth and development. Alaska and Snow pea (Pisum sativum) and New
Yorker and Better Boy tomato (Lycopersicum esculentum) plants, were grown from seeds under controlled environments in the Duke
University Phytotron. The results produced by CO2 enrichment were: 1) Apical dominance was not altered, 2) Seedling emergence
was unaffected. However, the growth response in terms of plant height, leaf thickness, dry matter production and flowering varied
with the species and the cultivars within species and was inconsistent for determinate and indeterminate cultivars. While even
determinate and indeterminate plants were not consistent in their response, growth form of indeterminate plants was more affected. 3)
The water status was usually not affected by the CO2 level when the plants were well-watered. When water was withheld both total
leaf water and osmotic potential decreased, with a slower decrease under high CO2. Plants maintained a positive turgor potential under
high CO2 and did not wilt when water-stressed. The differences in water potentials apparently were due to reduced stomatal
conductance and transpiration rate. Additional CO2 caused no effect on branch number in stressed or non-stressed plants. Water stress
completely inhibited branch development in pea and significantly reduced it in tomato. Elevated CO2 partially compensated for this
inhibiting effect and resulted in more rapid recovery of water-stressed plants. These results are of ecological significance. They
indicated that as atmospheric CO2 increases, there will be improved water use efficiency, and also, changes in canopy shape may
occur in crop stands and native ecosystems. This would be due to response differences of species, varieties and cultivars.

Major Professor(s): Hellmers, Henry
Department: Botany
Principal Investigator(s): Strain, Boyd R.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: ATMOSPHERE, CARBON DIOXIDE, FERTILIZATION, GROWTH AND DEVELOPMENT, VEGETATION,
WATER STRESS


13   
Bisbal, Evelin Cabrera. 1987. Effects of Subambient and Superambient CO2 Levels on Growth, Development and Total
Nonstructural Carbohydrate of Soybean. M.S. Thesis, University of Florida, 144 pages.

Atmospheric carbon dioxide (CO2) concentration has been increasing for the past 100 years and may double by the year 2030
according to some scenarios. Carbon dioxide enrichment studies can provide information on future crop yield responses as well as
quantify the limitation of low concentration of atmospheric CO2 on crop photosynthetic capacity. Soybeans [Glycine max (L.) Merr.
'Bragg'] were grown from seedling to maturity in sunlit environmentally controlled growth chambers under subambient (160, 220,
280 æmol 
mol-1), ambient (330 æmol mol-1) and superambient (660, 990 æmol mol-1) CO2 concentrations. The objectives were to determine the
effects of subambient and superambient CO2 concentration on (1) seasonal pattern of dry matter distribution, leaf growth, and
development stages, and (2) seasonal and diurnal patterns of total nonstructural carbohydrate (TNC) concentration. Morning and
evening plant samples were taken at eight dates. The plants were separated into components to determine dry matter accumulation
and leaf area extension, and then analyzed for TNC concentration in each plant component. Carbon dioxide enrichment increased dry
matter accumulation in all the vegetative plant parts as well as seed yield. Total plant dry weight increased more rapidly and to a
greater final biomass in plants that were exposed to superambient CO2 treatment. Plant height and leaf area were also increased by
elevated CO2 concentrations. Mainstem height increase in superambient CO2 concentration resulted from greater node number and
internode elongation. The increased sizes of plants in superambient CO2 concentrations were due to higher absolute growth rates,
which were associated with higher rates of leaf area development. Superambient CO2 caused a significant increase in the number of
nodes and branches, which represented additional sites for pod initiation and leaf area to support pod development. The yield increase
arose primarily because of increased seed number rather than seed size. However, harvest index was not altered by increase of CO2
and apparently dry matter partitioning between the seeds and other plant parts was not responsive to CO2 increase. Plants in
superambient CO2 accumulated more TNC than ambient and subambient throughout their development. These carbohydrates were
presumably utilized to support the growth of greater number of seeds. However, leaves of plants in superambient CO2 contained large
pools of TNC at plant maturity, indicating that not all of the photosynthetically derived carbohydrate reserves were utilized for seed
yield.

Major Professor(s): Allen, Leon H., Jr.
Department: Agronomy
Principal Investigator(s): Allen, Leon H., Jr.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: ATMOSPHERE, BIOMASS, CARBOHYDRATES, CARBON DIOXIDE, FERTILIZATION, GROWTH AND
DEVELOPMENT, LEAVES, SEEDS, VEGETATION, YIELD



14   
Blasch, Kyle W. 1994. Analysis of the Earth's Schumann resonance. M.S. Thesis, Massachusetts Institute of Technology, 192
pages.

Descriptions of two formulations describing the Earth's Schumann resonance were investigated to provide a quantitative analysis of
the resonance. The convective instability approach predicted higher values for the resonance than the absolute instability approaches.
Ratios methods for determining the frequency dependent source term, M(w), and attenuation were developed for the single source
case. The geometric structure of the resonance was used to isolate time periods and locations when the ratios closely approximated the
single source case. Quantitative comparisons were made with observed Schumann Resonance data from Table Mountain, California
and N.W. Cape, Australia. Agreement was within an order of magnitude for features in the first three modes, although ratios near the
singularities tended to overestimate the observed values.

Major Professor(s): Williams, Earle
Department: Earth, Atmospheric, and Planetary Sciences
Principal Investigator(s): Williams, Earle
Program Area: National Institute for Global Environmental Change (NIGEC)

KEYWORDS: SCHUMANN RESONANCE


15   
Boden, Thomas A. 1985. An Internship with the Carbon Dioxide Information Center at Oak Ridge National Laboratory. M.En.
Report, Miami University, 115 pages.

The objective of the Carbon Dioxide Information Center (CDIC) at Oak Ridge National Laboratory is to compile and distribute CO2-related information under systematic quality control to international researchers and policy makers evaluating direct and indirect
effects of increased CO2 levels. During a one-year internship beginning July 31, 1984, I helped compile, evaluate, and distribute
numeric data and computer model packages. These packages provide well-documented, retrievable CO2 databases and computer
models to researchers and help assure the long-term availability of documented CO2 data. In compiling six packages, I read CO2
research papers, wrote abstracts to document CO2 databases, wrote FORTRAN retrieval programs, developed graphics, and
synthesized materials into a document format. This experience helped me to develop programming and technical writing skills and to
expand my scientific knowledge. One package is included in this report as an example

Major Professor(s): Vankat, John L.
Department: Institute of Environmental Sciences
Principal Investigator(s): Farrell, Michael P.
Program Area: Information

KEYWORDS: CARBON DIOXIDE, DATABASES, MODELS


16   
Brakke, Mary P. 1989. Gas Exchange and Growth Responses of Citrus Trees to Partial Irrigation, Soil Water, and Atmospheric
Conditions. Ph.D. Dissertation, University of Florida, 181 pages.

Growth and yield of citrus trees in Florida have been reported to be closely related to the portion of rooting zone irrigated, contrary to
conclusions of many partial irrigation studies conducted elsewhere. This study was conducted to clarify whole plant gas exchange and
growth responses of young citrus trees to partial irrigation of the rooting zone and to investigate the influence of soil water and
atmospheric factors on gas exchange through experiments in controlled-environment growth chambers and model simulations of leaf
conductance and transpiration. In an initial study with fully irrigated citrus and three dry-bulb temperature/vapor pressure deficit
(DBT/VPD) treatment levels, photosynthetic rates and water-use efficiencies were greatest at the low DBT/VPD 
(24 øC/1.7 kPa) treatment and remained high when soil water content was low. Increases in DBT and VPD reduced photosynthetic
rate and water-use efficiency and resulted in photosynthetic midday depression at the intermediate (29 øC/2.4 kPa) and high (37
øC/3.6 kPa) DBT/VPD levels when soil water content was low. In a subsequent study, photosynthetic rate and growth of partially
irrigated trees on builders' sand declined significantly as the irrigated fraction of rooting volume was reduced 25, 50, and 75 percent.
Trees at all levels of irrigation and soil water content experiences severe midday depression of photosynthesis. In both studies,
transpiration increased, but not proportionally, as DBT/VPD increased and was attributed to stomatal closure. At elevated atmospheric
carbon dioxide concentrations, midday depression of photosynthesis was observed in the second study, but not in the initial study. The
combined findings suggest that midday depression of photosynthesis in citrus results in part from stomatal closure at elevated leaf-to-air humidity deficits, but perhaps more significantly, from increased mesophyll resistance induced by low soil water availability at
DBT/VPD levels about 24 øC/1.7 kPa. Simulated diurnal transpiration rates agreed closely with actual rates of trees with all or 3/4 of
their rooting-volume irrigated but declined more rapidly than actual rates in 2/4 or 1.4 irrigated trees. Results of simulations suggest
that soil type, evaporative demand, and root-length density are important factors influencing transpiration of fully and partially
irrigated citrus trees.

Major Professor(s): Allen, Leon H., Jr.
Department: Agronomy
Principal Investigator(s): Allen, Leon H., Jr.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: GROWTH AND DEVELOPMENT, LEAVES, MODELS, SOILS, TEMPERATURE, TRANSPIRATION, VAPOR
PRESSURE, VEGETATION, WATER, WATER STRESS, WATER USE


17   
Bremer, D. J. 1994. Transpiration from a Tallgrass Prairie Exposed to Elevated and Ambient Atmospheric CO2. M.S. Thesis, Kansas
State University, 110 pages.

Increasing concentrations of atmospheric CO2 may influence plant-water relations in natural and agricultural ecosystems. A tallgrass
prairie near Manhattan, Kansas was exposed to elevated atmospheric CO2 using open-top chambers (OTC's). Heat balance sap flow
gauges were used to measure transpiration in ironweed (Vernonia baldwini var. interior (Small) Schub.), a C3 forb; and on individual
culms of big bluestem (Andropogon gerardii Vitman) and indiangrass (Sorghastrum nutans (L.) Nash), both C4 grasses, in each of
three treatments: (1) CE (chamber enriched, 2x ambient CO2); (2) CA (chamber ambient, no CO2 enrichment); and (3) NC (no
chamber, no CO2 enrichment). Sap flow data were combined with measurements of stomatal resistance and whole-chamber
evapotranspiration (ET) to determine the effect of CO2 on water use at different scales. Because of frequent rainfall during the study,
all data were collected under well-watered conditions. Sap flow was reduced by 33% in ironweed, 18% in big bluestem, and 22% in
indiangrass under CO2 enrichment. Elevated CO2 reduced whole chamber ET by 23-27%. The environmental effect of the OTC
reduced transpiration by 21-24%. Stomatal conductance declined from 6.6 mm s-1 to 3.2 mm s-1 in big bluestem, and from 5.0 mm s-1
to 3.1 mm s-1 in indiangrass, under CO2 enrichment. Whole-plant stomatal resistance to water vapor flux (rp) was calculated from sap
flow measurements and environmental data collected in the chambers. Whole-plant stomatal resistance in big bluestem increased from
103 s m-1 to 194 s m-1 under elevated CO2 during sap flow measurements. Whole-plant stomatal resistance was scaled to the canopy
level, but consistently underestimated the canopy resistance calculated from whole-chamber ET data, indicating that rp in big bluestem
may not be representative of rp in other plants or species in the chamber. Elevated CO2 increased whole-chamber canopy resistance
more than scaled-up canopy resistance. Thus, elevated CO2 probably increases stomatal resistance in other species in the OTC more
than that of big bluestem. As atmospheric CO2 increases, CO2-induced stomatal closure may alter plant-water relations and the water
balance of an ecosystem.

Major Professor(s): Ham, J.M.
Department: Agronomy
Principal Investigator(s): Owensby, C.E.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: C3 METABOLISM, C4 METABOLISM, CARBON DIOXIDE, PRAIRIES, SAP, TRANSPIRATION, VEGETATION


18   
Bub, Frank Lee. 1993. The Structure of Water Mass, Salt, and Temperature Transports Within Intermediate Depths of the Western
Tropical Atlantic Ocean. Ph.D. Dissertation, University of New Hampshire, 222 pages.

Water mass flow patterns within the 150-1300 m intermediate layer of the western tropical Atlantic were determined from
observations during four 1990-1991 Pegasus velocity and CTD hydrographic surveys. Non-divergent flows were analyzed to
determine transports. A survey-average 29 Sverdrups (1 Sv = 106 m3/s) of southern hemisphere water masses flowed northwestward
across 44øW near the equator as part of the subsurface South Equatorial Current (SEC). 21 Sv retroflected anticyclonically around
the Amazon Eddy (2øN 45øW) and flowed eastward toward the North Equatorial Undercurrent (NEUC). The other 8 Sv moved
northwestward within a series of anticyclonic retroflection eddies which periodically separate from the Amazon Eddy. 61 Sv of a
northern/southern water mass mixture flowed southeastward across 9øN as part of the North Equatorial Current (NEC) and
bifurcated; 32 Sv turned anticyclonically northwestward, and 29 Sv turned cyclonically around a low (6øN 44øW), merged with the
southern water, and flowed toward the NEUC. The 50 Sv NEUC, a mixture of mostly southern water, flowed eastward into the
interior. The remaining NEC and SEC branches blended to form a 40 Sv northwestward transport across 53øW. These observed
transports were generally about three times larger than the wind-driven equatorial and tropical gyre return transports (Mayer and
Weisberg 1993); suggesting the existence of subgyre-scale recirculation eddies in the western tropics. One of the retroflection eddies
was measured during September 1990. Its structure was approximated by a 300 km diameter cylinder which extended vertically
through the surface and intermediate layers to 1300 m. During two other surveys, retroflection eddies were identified at the region's
northwestern corner. Instantaneous transport associated with an eddy which translated at 10 cm/s was about 30 Sv. Assuming three
were generated each year, retroflection eddy translation could account for the 8 Sv alongshore flow through the region. According to
water mass budgets, 21 Sv of northern water masses were transformed by mixing within the region. Temperature-salinity
relationships indicated this mixing effectively transports the cool, low salinity Antarctic Intermediate Water into the North Atlantic by
as yet unknown pathways.

Major Professor(s): Brown, Wendell S.
Department: Earth Sciences
Principal Investigator(s): Moore, Berrien
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: CIRCULATION, MASS, OCEANS, SALINITY, TEMPERATURE, TROPICS, WATER


19   
Burns, Kerry Lee. 1994. Cloud Microstructure, Acidity and Reflectivity: Case Studies and Implications for Regional Climate
Change. M.S. Thesis, North Carolina State University, 36 pages.

A sensitivity analysis was performed to determine the effect of small fluctuations in cloud microphysical parameters on the cloud
albedo. It is discovered that unpolluted marine clouds should have a greater radiative response to changes in cloud droplet spectra than
more polluted continental clouds. It is further shown that increasing droplet concentration by a few percent can have a greatly
increased cloud albedo and produce a cooling effect on regional climate. In situ cloud measurements were taken during 39 individual
cloud events between June and October 1993 in Mount Mitchell State Park, North Carolina. Cloud droplet spectra were measured
coincidentally with cloud water pH and chemical composition. A total of 113 hourly cases were recorded. Nine of these cases
corresponded with satellite derived direct cloud albedo measurements. Scatter graphs were generated showing how albedo varies with
cloud droplet concentration, cloud droplet size, cloud liquid water content, cloud water pH, cloud thickness, and precursor cloud
condensation nuclei concentration.

Major Professor(s): Saxena, Vinod K.
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Saxena, Vinod K.
Program Area: National Institute for Global Environmental Change (NIGEC)

KEYWORDS: AEROSOLS, CHEMISTRY, CLIMATE, CLOUDS, CONDENSATION, MICROPHYSICS, PARTICULATES,
REFLECTANCE, WATER


20   
Byun, Dae-Won. 1983. A Two-Dimensional Mesoscale Numerical Model of St. Louis Urban Mixed Layer. M.S. Thesis, North
Carolina State University, 216 pages.

An urban boundary layer (UBL) is characterized by a smaller surface albedo than rural, large sensible heat flux due to the urban
surface medium and small moisture availability, inhomogeneity of the surroundings, additional anthropogenic heat and considerably
large surface roughness attributed to buildings and man made structures. A horizontal two dimensional numerical UBL model of St.
Louis., which takes into account above differences of the urban from the rural, is developed based on the mixed layer assumption. For
numerical integration, the time splitting technique is used in which the system is decomposed into an adjustment stage, a flux
exchange stage and an advection stage. A cubic spline upstream advection scheme, which allows better choice of smoothing and
boundary conditions than Mahrer and Pielke's (1978), is tested and utilized. The land use differences over the metropolitan area are
characterized by the different proportions of the concrete and grassy soil surfaces. The thermal parameters of the vegetated soil are
parameterized in terms of surface soil moisture content. From the homogeneous case studies. distinct urban and rural patterns of
surface energy budget, which are typical of some observational studies, are obtained. It suggests that the simplification is successful in
simulating the effects of different land use types on the atmosphere. Dynamics of a dome shaped model urban mixed layer is studied
with the stationary balanced wind. It seems that the balanced wind can explain some important flow perturbations due to the urban
heat island. Numerical simulation of the daytime boundary layer of St. Louis, Mo. on August 18, 1976, show some favorable results.
The simulated wind field shows a heat island-related weak convergent area, complicated with the topographical effects, over the
southwest side of the city in the morning. The model predicts surface temperature distributions similar to the observations showing a
distinct surface urban heat island, although contour patterns differ from observations in detail. Downwind displacements of the mixed
layer dome and urban plume phenomenon are simulated. However, influence of existing topography further complicated the mixed
layer thickness patterns, especially in the morning. Further, the effects of only the urban heat island on the mixed layer evolution are
studied by removing the topography in one simulation. The results of the run without topography show that the locations of local
maxima and minima in mixed layer heights and temperatures coincide one another, suggesting existence of a direct relation between
the two fields. In the morning, when the distinct mixed layer dome and high potential temperature region were present at the
downwind side of the city, significant convergent flow is seen over that area. In the afternoon, the wind field is characterized by a
nearly nondivergent and relatively homogeneous flow. The results here demonstrate the usefulness/potential of the vertically-integrated model for simulation of the clear day mixed layer. For such cases the present model can give increased understanding of the
interrelationships between physical parameters determining the urban heat island phenomenon. For nighttime periods or morning and
evening transition periods, a three-dimensional large eddy simulation model may be necessary.

Major Professor(s): Arya, S.P.S.
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Pietrafesa, Leonard J.
Program Area: Marine Transport

KEYWORDS: ATMOSPHERE, BOUNDARY LAYER, CLIMATE, LAND SURFACE, LAND USE, MODELS, SPATIAL
DISTRIBUTION, URBAN ENVIRONMENT


21   
Campbell, William J., Jr. 1986. Effects of Carbon Dioxide on the Physiology and Biochemistry of Photosynthesis in Soybean.
Ph.D. Dissertation, University of Florida, 181 pages.

In three consecutive years (1983, 1984, and 1985) soybeans (Glycine max L. Merr. cv Bragg) were grown from seed to maturity in
six outdoor environmentally controlled plant growth chambers under natural solar irradiance. The CO2 concentrations inside the
chambers were controlled to various levels during these studies. Both field and laboratory measurements were made to investigate the
effects of CO2 concentration on photosynthesis. Emphasis was placed on the response to CO2 of ribulose 1,5-bisphosphate (RuBP)
and RuBP carboxylase (RuBPCase), the substrate and enzyme of the carbon fixation reaction in soybean. Following growth at 330
(atmospheric concentration) or 660 æl CO2 l-1, leaflet photosynthetic rates were always greater for the elevated CO2 grown plants
when measured over a wide range of CO2 concentrations. This enhanced capacity for photosynthesis was possibly a result of changes
in internal leaf anatomy, or to greater assimilate demand, or both, in the high CO2 grown plants. The RuBP concentration decreased
with increasing CO2, but still appeared to be greater than the active site concentration of RuBPCase. The RuBPCase activity,
expressed on an area basis, was not affected by growth CO2 concentration. It appears that RuBPCase and RuBP are thus not involved
significantly in the enhanced photosynthetic capacity. Evaporative cooling kept leaf temperatures from reaching the higher air
temperatures during studies on temperature effects on soybean growth at atmospheric and twice atmospheric concentrations of CO2.
Although air temperatures were increased by approximately 5 and 10øC, leaf temperatures were usually not increased more than
approximately 2.5 and 4.5øC, respectively. These leaf temperature increases were not great enough to affect canopy photosynthesis or
RuBPCase activity (on a chlorophyll basis) in either CO2 treatment. Canopy photosynthesis was, however, greater at the higher CO2
concentration. The concentration of RuBP was reduced at higher temperatures. Increasing growth CO2 concentrations (from 160 to
990 æl CO2 l-1) resulted in decreasing RuBPCase activities and RuBP levels, when both were expressed on a chlorophyll basis. At the
higher CO2 concentrations, the concentration of RuBP appeared to approach the concentration of RuBPCase active sites. Both the
apparent Km(CO2) and Vmax of RuBPCase showed small, but statistically significant, decreases with increasing CO2.

Major Professor(s): Allen, Leon H., Jr.
Department: Agronomy
Principal Investigator(s): Allen, Leon H., Jr.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: ATMOSPHERE, CARBON DIOXIDE, ENZYMES, GROWTH AND DEVELOPMENT, LEAVES,
PHOTOSYNTHESIS, RIBULOSE BISPHOSPHATE, TEMPERATURE, VEGETATION


22   
Chaloupka, Kristin A. 1994. Diagenetic Behavior of Arsenic in Amazon Shelf and Long Island Sound Sediments. M.S. Thesis,
State University of New York at Stony Brook, 90 pages.

Arsenic cycling in sediments is influenced by a variety of physical and chemical processes. Anthropogenic activities are also potentially
important. In order to help elucidate major controls on diagenetic behavior of arsenic, vertical profiles of total dissolved and solid
phase arsenic were measured in two physically distinct environments; the Amazon shelf and Long Island Sound. The relative trends of
arsenic distributions were similar in both study sites, with subsurface pore water maxima and surficial solid phase enrichment. In
Amazon shelf sediments, these patterns reflect a strong redox association with iron whereby oxidized arsenic is adsorbed onto iron
oxyhydroxides in surface sediments, which is then subsequently reduced and dissolved upon burial in the sub-oxic zone. Upward
diffusion within the sediment is followed by readsorption or release to the water column. On the Amazon shelf, intense physical
reworking of sediments often releases the dissolved arsenic fraction to the water column. In contrast, loss of arsenic from sediments in
Long Island Sound does not reflect an energetic environment. Instead, it is linked to annual fluctuations in temperature and organic
carbon inputs which, when high, deplete the oxygenated zone within the sediment, and result in an upward shift in redox processes. In
addition to iron, arsenic is also closely coupled to the manganese and phosphate cycles in Long Island Sound; relationships which
deteriorate following a bloom event. Fluxes of dissolved arsenic from Long Island Sound sediment, calculated from pore water profiles
during periods of elevated organic carbon deposition, are on the order of 0.025-0.634 æmol/m2/d, while the flux from the solid phase
into pore water is 1.42-11.5 æmol/m2/d. Disparity between these rates may reflect the fact that the flux calculations exclude irrigation
rates, adsorption onto additional mineral phases, physical reworking of sediments, among other model assumptions. Pore water As
concentrations in Amazon shelf sediments are an order of magnitude greater than for sediments in Long Island Sound, and elevated
concentrations extend several meters below the sediment surface. These expanded features are probably due to the combined effects
of intense chemical weathering of riverine sediments and a turbulent physical regime present on the shelf, both of which promote Fe
cycling. Annual fluctuations in river flow result in increased physical mixing of the sediments during higher flow, and a greater
abundance of benthic biota during lower river flow, particularly away from the river mouth. This results in generally increasing arsenic
pore water concentrations away from the river. Patterns of temporal variability are more difficult to discern, possibly due to differences
in physical environments on the shelf. While some areas of the shelf are generally controlled by sediment transport processes, other
areas are influenced more by benthic activity.

Major Professor(s): Aller, Robert C.
Department: Marine Sciences
Principal Investigator(s): Aller, R.C., J.K. Cochran, J.Y. Aller, and C. Lee
Program Area: Marine Transport

KEYWORDS: DIAGENESIS, METALS, NORTH AMERICA, OCEANS, ORGANICS, PHOSPHATE, REMOBILIZATION, RIVERS,
SEDIMENTS, SOUTH AMERICA, TEMPORAL DISTRIBUTION


23   
Chanumalla, Neeraja Reddy. 1992. A Study of Mesoscale Circulation and the Structure of the Baroclinic Boundary Layer over a
Gulf Stream Filament. M.S. Thesis, North Carolina State University, 148 pages.

Observations obtained from aircraft, buoys, ships and vertical soundings made from 9-11 February, 1986 during the Genesis of
Atlantic Lows Experiment (GALE) were used to study the mesoscale circulations and the mean and turbulent marine boundary layer
structure over the cold coastal waters and the warm Gulf Stream. Different synoptic conditions prevailed on each day. The synoptic
setting was characterized by prestorm conditions on 9 February, meso low development on 10 February and offshore cyclogenesis on
11 February. A Gulf Stream filament about 150 km long and 50 km wide was also formed during this period. Analysis of the data on
10 February indicates substantial increase in wind speed and change in direction across the filament up to a height of about 300 m.
Northeasterly synoptic winds changed to a northwesterly direction, with winds almost at right angles to the filament. This in
combination with the effects of the horizontal temperature gradients between the coastal waters, the cold core of the filament and the
Gulf Stream appears to have induced a mesoscale cyclonic circulation. Wind speeds indicated a low level convergence over the
filament. This mesoscale circulation and the convergence appears to have caused a meso-low over the filament which later developed
into a mid-latitude cyclone when a mid-tropospheric trough advected into the region on 11 February. Turbulence profiles indicated
that the similarity relations are valid during undisturbed weather. During disturbed conditions on 10 February and 11 February
variances do not seem to follow the free convection relations. Conventional similarity relations with the height normalized by the
boundary layer height did not exist during meso-low development and offshore cyclogenesis.

Major Professor(s): Raman, Sethu
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Raman, Sethu
Program Area: Atmospheric Radiation Measurement (ARM)

KEYWORDS: ATMOSPHERE, BOUNDARY LAYER, CIRCULATION, CLIMATE, MARINE ENVIRONMENT, OCEANS,
PRESSURE, STORMS


24   
Charney, Joseph J. 1992. Heating Rate Variability in Radiation Codes When Subjected to Different Vertical Discretizations. M.S.
Thesis, University of Maryland at College Park, 43 pages.

A collection of seven radiation codes was acquired from various organizations and intercompared. Their variability with respect to
each other was determined when performing heating rate calculations on different distributions of vertical levels. Specifically, two
vertical discretizations with 30 and 18 levels were intercompared. Some significant differences were found to exist by performing
simple statistical tests on the models. The statistical tests were based on sets of 100 heating rate calculations. Independent
determinations were made at each model level. The parameterizations of water vapor absorptivities were found to cause the largest
variability between the models. Other mechanical problems were highlighted and recommendations for future steps in the ongoing
study were proposed.

Major Professor(s): Baer, Ferdinand
Department: Meteorology
Principal Investigator(s): Baer, Ferdinand
Program Area: Atmospheric Radiation Measurement (ARM)

KEYWORDS: CLIMATE, HEAT FLUX, MODELS, RADIATIVE PROCESSES


25   
Chen, Liqiang. 1994. The Simulation of Reflection Function of Clouds Using the Adding-Doubling Method. M.S. Thesis, South
Dakota School of Mines and Technology, 57 pages.

Clouds reflect about 50% of the incident solar radiation and thus account for most of the planetary albedo. The investigation of energy
reflected by clouds is very important to estimate the global climate change. The plane parallel assumption is widely used in both model
and remote sensing studies for calculating cloud reflections. The objective of this study is to use AVHRR data to test the plane parallel
assumption. The AVHRR Channel 1 data is used, which has the wavelength of 0.58æm-0.68æm. In order to test the plane parallel
assumption, a radiative transfer model is used. The model considers ozone absorption and the atmospheric molecular scattering. There
are three layers in the model, in which layer ozone absorption, the molecular scattering and Mie scattering are independently
processed. The reflection function, defined as the ratio of the reflected radiance to the incident solar radiance, is used to describe the
angular dependence of the reflected radiation. The adding-doubling method is used to deal with multiple scattering. One month of the
AVHRR data is averaged for different solar and satellite viewing zenith angles as well as relative azimuth angles in order to obtain an
averaged reflection function. The model results show that the reflection function depends on the cloud optical thickness. The
comparison between the model results and the AVHRR data shows that at larger solar zenith angle the plane parallel assumption
causes larger error. However, on average, cloud optical thickness derived from plane parallel assumption does not show significant
bias.

Major Professor(s): Han, Qingyuan
Department: Meteorology
Principal Investigator(s): Han, Qingyuan
Program Area: National Institute for Global Environmental Change (NIGEC)

KEYWORDS: CLOUDS, MODELS, OZONE, RADIATIVE PROCESSES, REFLECTANCE, SCATTERING


26   
Chen, Minghang. 1993. Cloud Radiative Forcing Anomalies Associated with and Their Effects on the Atmospheric Response to
Equatorial Pacific SST Anomalies. Ph.D. Dissertation, State University of New York at Stony Brook, 142 pages.

The NCAR CCM2 has been used in this study to investigate cloud radiative forcing (CRF) anomalies associated with equatorial
Pacific SST anomalies, and the effects of the longwave CRF (LWCRF) anomalies on the atmospheric response to the SST anomalies.
The SST anomalies cause large CRF anomalies, both longwave and shortwave, as well as latent heat anomalies at low latitudes on a
global scale. The relative magnitude of the simulated longwave and shortwave CRF anomalies is consistent with the result of the
Earth Radiation Budget Experiment (ERBE), which means cloud height and cloud radiative properties, such as emissivity and
reflectivity, are well simulated by the model. The CRF anomalies, however, are underestimated in the CCM2. This underestimate of
the CRF anomalies is due to the insufficient high cloud amount anomaly in the model. The LWCRF anomaly strongly enhances the
precipitation anomaly in the whole tropical belt. The positive (negative) LWCRF anomaly warms (cools) the troposphere and
destabilizes (stabilizes) the upper troposphere. The LWCRF anomaly enhances the Southern Oscillation, both the positive sea level
pressure (SLP) anomaly in the Indonesia-Australia region and the negative SLP anomaly in the central and eastern Pacific, and the
related Walker circulation anomaly. The effects of the LWCRF anomaly are essential to the NH extratropical circulation anomaly, the
PNA pattern. The LWCRF anomaly has a large contribution to the three action centers of the PNA pattern, especially the positive
anomaly center, at all levels. This large contribution results from the direct thermal effect of the tropical LWCRF anomaly and its
strong positive interaction with tropical deep convection. As a consequence of the complex interaction between the forced wave train,
orographic forcing and other factors, the contribution rates of the LWCRF anomaly to the three PNA action centers are different.

Major Professor(s): Cess, Robert D.
Department: Coastal Oceanography (Atmospheric Sciences)
Principal Investigator(s): Cess, Robert D.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: CLOUDS, RADIATIVE PROCESSES


27   
Chen, M. 1994. Validation and Adjustment of Precipitation Simulated by CCM2/BATS over the Continental United States. M.S.
Thesis, University of Arizona, 86 pages.

This study compares frequency, intensity and amount of precipitation simulated by NCAR CCM2/BATS with those observed over the
continental United States. The emphasis is placed on both spatial and temporal variations. The analysis indicates that: a) The model
simulates the seasonal variation of daily intensity reasonably well, while the seasonal variation of frequency is poorly produced. b) The
model underestimates the amplitude of intensity, overestimates the amplitude of frequency, and distorts the distribution of phase in
diurnal variations. c)The simulated maximum hourly precipitation has almost the same range as is observed. However, the model fails
to simulate the overall pattern of maximum hourly precipitation, maximum wet and dry periods from observations. d)The model
overestimates the frequency of hourly precipitation by a factor of 13-48 and underestimates intensity by about 90%.These results
demonstrate a necessity to adjust simulated precipitation for realistic surface simulation. After adjustment, the simulated intensity is in
much closer agreement to the observed value.

Major Professor(s): Dickinson, Robert E.
Department: Atmospheric Sciences
Principal Investigator(s): Dickinson, Robert E.
Program Area: Computer Hardware, Advanced Mathematics, and Model Physics (CHAMMP)

KEYWORDS: CLIMATE, MODELS, PRECIPITATION, SPATIAL DISTRIBUTION, TEMPORAL DISTRIBUTION


28   
Cione, Joseph Jerome. 1992. The Effects of Surface Forcing on Mid-Atlantic Winter Cyclones. M.S. Thesis, North Carolina State
University, 120 pages.

Mid-latitude cyclones develop off the Carolinas during winters and move north producing gale force winds, ice and heavy snow. It is
believed that boundary layer and air-sea interaction processes are very important during the pre-cyclonic and development stages of
these east coast storms. Due to the presence of the Gulf Stream, the marine boundary layer just offshore is highly baroclinic caused by
warmer sea surface temperatures relative to the coastal waters. The offshore flow during cold air outbreak (CAO) periods initiates a
strong heat flux distribution in the Western Atlantic Ocean that, over time, acts to vertically warm and moisten the atmosphere from
below (Whittmann, 1982; Vukovich et al., 1991; Wayland and Raman, 1989; Holt and Raman, 1990). This airmass modification has
been observed to substantially reduce regional stabilities over a time scale of 36 to 48 hours. This thesis looks into the effects the
presence of the Gulf Stream off the Virginia and Carolina coastlines during the pre-storm environment potentially has on the
intensification of coastal cyclones. The examination of nine years of data on the Gulf Stream position and east coast winter storms
seems to indicate that the degree of low level baroclinicity and modification existing prior to a cyclonic event significantly affects the
rate of cyclonic deepening off the mid-Atlantic coastline.

Major Professor(s): Raman, Sethu
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Pietrafesa, Leonard J.
Program Area: Marine Transport

KEYWORDS: ATMOSPHERE, BOUNDARY LAYER, CIRCULATION, CLIMATE, COASTAL ENVIRONMENT, MARINE
ENVIRONMENT, OCEANS, PRESSURE, STORMS


29   
Collins, Dan C. 1992. An Evaluation with the Fourier Amplitude Sensitivity Test (FAST) of Which Land-Surface Parameters Are of
Greatest Importance for Atmospheric Models. M.S. Thesis, Rutgers University, 78 pages.

Land-surface parameterizations based on a statistical-dynamical approach have been suggested recently to improve the representation
of the surface forcing from heterogeneous land in atmospheric models. With this approach, land-surface characteristics are prescribed
by probability density functions (pdf's) rather than single "representative'' values as in "big-leaf'' parameterizations. Yet the use of many
pdf's results in an increased computational burden and requires the complex problem of representing covariances between pdf's to be
addressed. In this study, a sensitivity analysis of a land-surface parameterization for atmospheric modeling was performed to evaluate
the surface parameters most important to the variability of surface heat fluxes. The Fourier Amplitude Sensitivity Test (FAST) used
for this analysis determines the relative contribution of individual input parameters to the variance of energy fluxes resulting from a
heterogeneous surface. By simultaneously varying all parameters according to their individual probability density functions, the
number of computations needed is very much reduced by this technique. This analysis demonstrates that most of the variability of
surface heat fluxes may be described by the distributions of relative stomatal conductance and surface roughness. Thus, the statistical-dynamical approach may be simplified by the use of only these two probability density functions.

Major Professor(s): Avissar, Roni
Department: Meteorology and Physical Oceanography
Principal Investigator(s): Avissar, Roni
Program Area: Computer Hardware, Advanced Mathematics, and Model Physics (CHAMMP)

KEYWORDS: ATMOSPHERE, FOURIER AMPLITUDE, HEAT FLUX, LAND SURFACE, MODELS, SOILS, TURBULENCE,
VEGETATION


30   
Comstock, Jonathan Paul. 1985. Photosynthetic and Whole-Canopy Responses to Changing Plant Water status in Desert Shrub.
M.S. Thesis, University of Utah, 80 pages.

The effects of changing plant water relations on plant carbon gain were studied in Encelia frutescens (Gray) with respect to both
physiological performance during periods of slowly declining plant water potential, and the phenology of leaf production and death
associated with natural rainfall in a warm desert. Physiological studies of the photosynthetic responses of individual leaves to
increasing water stress were carried out on potted plants at the University of Utah. Light-saturated CO2 assimilation rates decreased
from 42.6 ñ 1.6 æmol CO2 m-2 s-1 (x ñ s.e.) to 1.7 ñ 1.7 æmol CO2 m-2 s-1 as leaf water potentials decreased from -1.5 MPa to -4.0
MPa. This decline in net photosynthesis was shown to arise from both stomatal and nonstomatal effects, but not to equal degrees. The
relative stomatal limitation, defined as the percent limitation in photosynthetic rate due to the presence of gas-phase diffusional
barriers, increased from 11 ñ 2 (x ñ s.e.) to 41 ñ 3% as water potentials became more negative. The importance of declining
physiological capacity for photosynthesis in limiting whole-plant carbon gain was further studied in an experimental garden plot
located in the Sonoran Desert at the Phoenix Desert Botanic Garden. The production and longevity of leaves of E. frutescens were
followed under the natural rainfall regime during the summer and fall of 1984. The relationships between seasonally changing plant
water status, extent of canopy development, and photosynthetic capacity per unit leaf area were determined. Maximum leaf life spans
during a summer activity period were between 3 and 4 months, with the great majority living between 1 and 3 months. Leaf
production occurred synchronously in well-defined cohorts triggered by precipitation events. Extensive leaf turnover occurred during
the summer period even though the plants remained in continuous leaf. Turnover was most pronounced when precipitation triggered
the production of new leaf cohorts. Five weeks were required for plants to reach maximum canopy development when renewed soil-water availability followed a prolonged drought. Photosynthetic capacity per unit leaf area recovered much sooner than total leaf area,
and submaximal leaf area development was the major factor limiting whole-plant carbon gain during a leaf-flushing period lasting
several weeks. As the soil began to dry out, physiological capacity declined more rapidly than leaf area, and became the primary
limiting factor to whole plant carbon gain.

Major Professor(s): Ehleringer, James R.
Department: Biology
Principal Investigator(s): Ehleringer, James R.
Program Area: Ecosystems Function and Response

KEYWORDS: CARBON CYCLE, DESERTS, GROWTH AND DEVELOPMENT, LEAVES, PHOTOSYNTHESIS,
PRECIPITATION, SOILS, VEGETATION, WATER STRESS


31   
Comstock, Jonathan Paul. 1989. Photosynthesis in Twigs. Ph.D. Dissertation, University of Utah, 132 pages.

Forty species from desert and adjacent riparian habitats were surveyed for twig photosynthetic activity. Photosynthetic capacity, as
indicated by an increase in the net CO2 assimilation rate (A) in the light, was found in the twigs of all species. In most nondesert
species, however, A was always negative. A was positive in the twigs of many desert species, which also exhibited specialized
anatomies. The phenology and assimilation rates of leaves and twigs capable of positive net uptake were followed for one year. Both
leaf and twig cohorts reached maximum values of surface area development and A in spring. The degree of drought related dieback
during summer varied among species for both leaves and twigs, but when A was positive in twigs, they were often more drought
resistant than leaves of that same species. A detailed comparison was made of leaves and twigs in a desert species with positive net
photosynthetic twigs, Hymenoclea salsola. Leaves had higher values of A and intercellular CO2 (ci) than twigs when plants were well
watered, and this may have been due to greater anatomical specialization in the leaves. When the twigs of a given species did not have
high stomatal densities and conductances, they always operated in the light with ci above ambient and A negative. As leaf size
increased among species, twig respiration rates and gross photosynthetic rates increased. When twig respiration rates were high,
photosynthetic nitrogen-use-efficiency may have been maximized by having twigs recycle endogenous CO2 at high ci, and only leaves
engaging in positive net uptake at ci below ambient.

Major Professor(s): Ehleringer, James R.
Department: Biology
Principal Investigator(s): Ehleringer, James R.
Program Area: Ecosystems Function and Response

KEYWORDS: CARBON CYCLE, DESERTS, GROWTH AND DEVELOPMENT, LEAVES, PHOTOSYNTHESIS,
PRECIPITATION, SOILS, VEGETATION, WATER STRESS


32   
Costigan, Keeley R. 1992. Large Eddy Simulations of the Atmospheric Boundary Layer East of the Colorado Rockies. Ph.D.
Dissertation, Colorado State University, 142 pages.

Large eddy simulation, LES, has often been carried out for the idealized situation of a simple convective boundary layer. Studies of
dual Doppler radar and aircraft data from the Phoenix II experiment indicate that the boundary layer of the Colorado High Plains is not
a purely convective boundary layer and it is influenced by the mountains to the west. The purpose of this study is to investigate the
atmospheric boundary layer on one particular day over the Colorado High Plains. This research applies a LES nested within larger
grids, which contain realistic topography and can simulate the larger-scale circulations initiated by the presence of the mountain
barrier. How and to what extent the atmospheric boundary layer of the Colorado High Plains is influenced by larger-scale circulations
and other phenomena associated with the mountain barrier to the west is investigated.

Major Professor(s): Cotton, William
Department: Atmospheric Sciences
Principal Investigator(s): Porch, William M.
Program Area: Quantitative Links

KEYWORDS: BOUNDARY LAYER, CIRCULATION, DIFFUSION, LAND SURFACE


33   
Cripe, Douglas G. 1994. Investigation of GCAPE Quasi-Equilibrium in the Midlatitudes. M.S. Thesis, Colorado State University,
230 pages.

Lorenz (1955, 1978, 1979) developed the concept of the "moist available energy" (MAE) of the atmosphere. This he defined as the
portion of non-kinetic energy (NKE) available for conversion to kinetic energy (KE). Randall and Wang (1992) and Wang and
Randall (1994) showed that it is possible to consider the component of the MAE that resides in the vertical structure of the
atmosphere as a "generalized convective available potential energy" (GCAPE). Using data from the tropics, they tested the GCAPE
quasi-equilibrium hypothesis (Arakawa and Schubert, 1974) which asserts that cumulus convection "consumes" GCAPE as quickly
as it is produced by large-scale (non-convective) forcing such that the convectively active atmosphere remains close to a state of
conditional neutrality. The main purpose of this study is to also investigate the GCAPE quasi-equilibrium hypothesis, only this time in
a midlatitude setting. This is a tougher test of the hypothesis given the significantly larger temperature and moisture fluctuations
resulting in a stronger large-scale forcing in the midlatitudes, compared with the tropics. Data recently made available by the
Atmospheric Radiation Measurement (ARM) program has been used. This new data comes from radiosonde measurements collected
at ARM's Cloud and Radiation Testbed (CART) site located in north-central Oklahoma during Intensive Operation Periods (IOPs) run
periodically throughout the year. Since this is one of the first studies to make extensive use of this data, a further goal was to evaluate
the quality of the wind and thermodynamic measurements being produced by the CART site. Additionally, analysis data from the
Mesoscale Analysis and Prediction System (MAPS) was used, both as a check on the reasonableness of the ARM data, and also to
detect any possible errors in the MAPS model output.

Major Professor(s): Randall, David A.
Department: Atmospheric Science
Principal Investigator(s): Randall, David A.
Program Area: Atmospheric Radiation Measurement (ARM)

KEYWORDS: CLIMATE, CLOUDS, CONVECTION, WINDS


34   
Crouzet, Yoan. 1993. Equilibrium Vapor Pressure and Capillary Ring Formation of Adhering Spherical Aerosol Particles. M.S.
Thesis, Texas A&M University, 130 pages.

Liquid rings trapped by capillary condensation at the point of contact between two spherical particles present an interesting feature
insofar as they often display negative curvatures, thereby inducing a lowering of the equilibrium vapor pressures according to the
Kelvin equation. This thesis work is divided up into two parts, and each part corresponds to a specific approach of the problem and
different objectives. The first part of this work dealt with the calculations of the mean curvature of the meniscus for any two spherical
particles in contact. Results were interpreted in terms of equilibrium vapor pressure and applied to condensation nuclei activation.
Critical supersaturations were defined and compared to the predictions of the heterogeneous nucleation model for the case of water. A
few applications were listed. The second part of this thesis work attempted a different approach by taking into consideration the van
der Waals interaction forces acting at a molecular level. The liquid was modeled as an assembly of one-nanometer liquid spheres, and
a Monte Carlo code was developed in order to find the minimal energy configuration of the system. Energies were computed using
Lifshitz theory between macroscopic spheres. A simulation was performed for a specific case: liquid water and two hexadecane solid
particles in contact. The final configuration of the assembly was first analyzed in order to estimate the contact angle; the interface was
then compared to the predictions of the previous approach. A very encouraging agreement was found on a qualitative level.

Major Professor(s): Marlow, William H.
Department: Nuclear Engineering
Principal Investigator(s): Marlow, William H.
Program Area: Atmospheric Sciences

KEYWORDS: AEROSOLS, CAPILLARITY, CONDENSATION, VAPOR PRESSURE


35   
Daniels, R. C. 1991. An Internship with the Carbon Dioxide Information Analysis and Research Program at Oak Ridge National
Laboratory: The Effects of Greenhouse Gas Induced Sea Level Rise on the South Carolina Coast. M.A. Report, Miami University,
174 pages.

This one-year internship was conducted at Oak Ridge National Laboratory, Oak Ridge, Tennessee, in the Environmental Sciences
Division (ESD). The internship consisted of four projects conducted in the following two programs within ESD: the Carbon Dioxide
Information Analysis Center (CDIAC) and the Resource Analysis Project. Two projects involved the production and/or updating of
two digital data sets designed for use in global warming research for CDIAC. In the third several of CDIAC's data sets were used to
examine the effects that volcanic aerosols and changes in solar irradiance could have on the Earth's global mean air temperature. The
last project (the bulk of this report) studies the effects that predicted sea level rise and episodic inundation (from tropical cyclones)
would have on two vulnerable areas in South Carolina in the year 2100.

Major Professor(s): Klink, John
Department: Geography
Principal Investigator(s): Kanciruk, Paul, and Robert M. Cushman
Program Area: Information; Carbon, Climate, and Vegetation

KEYWORDS: AEROSOLS, ATMOSPHERE, COASTAL ENVIRONMENT, DATABASES, RADIATIVE PROCESSES, SEA LEVEL,
STORMS, TEMPERATURE, VOLCANOES


36   
D'Arrigo, Rosanne Dorothy. 1989. Dendrochronologic Modeling and Reconstruction of Large-Scale Climate Variability in Recent
Centuries and Its Relation to Atmospheric Forcing Functions. Ph.D. Dissertation, Columbia University, 216 pages.

Tree-ring chronologies from boreal treeline and other sites have been used to reconstruct patterns of climate variability, their
relationship to known forcing functions, and climate as modeled using these forcings. Northern Hemisphere temperatures
reconstructed for the past three hundred years agree with other proxy data and with temperature derived from a radiative-convective
model incorporating volcanic, solar and CO2 forcings. Superposed epoch analysis shows the effects of volcanism on tree growth and
spectral analysis indicates periodicities which might be related to solar or other cycles. Comparison of the reconstructed temperatures
with recent instrumental records reveals that the temperature departures within the past decade of elevated atmospheric trace gases
levels exceed the "natural" variations in the tree-ring data in past centuries. A CO2 fertilization effect is not detected in this data
through 1973. This issue is further investigated for a high-elevation lodgepole pine site from California. Climate response models
indicate that a recent growth increase cannot be completely explained by past climate-growth relationships. The contribution of
atmosphere-biosphere CO2 exchange of boreal forests to Pt. Barrow CO2 amplitudes is found to be significant using a 3-D tracer
model which employs an exchange function based on remote sensing photosynthetic indices. Positive correlations between variations
in those amplitudes and tree-ring data suggest that tree-rings may be used as indicators of CO2 uptake and remote sensing estimates of
photosynthetic activity. The northern chronologies show patterns of variation which have climatic implications. Their coefficient of
variation reveals periods of agreement/disagreement among the sites which in turn indicates varying periods of spatial coherence in
atmospheric circulation patterns. Included among the years of highest variation is 1816, one year following the Tambora eruption. The
tree growth anomalies support the hypothesis of a shift in the atmospheric long wave pattern with enhanced meridional Arctic airflow
at this time. Internal variations of the climate system include the global-scale interactions associated with the El Nino-Southern
Oscillation and variations in the monsoon cycle. A Java teak tree-ring series shows a response to ENSO and monsoon precipitation.

Major Professor(s): Jacoby, G.
Department: Geology
Principal Investigator(s): Fung, Inez
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: CARBON DIOXIDE, CLIMATE, EL NI¥O - SOUTHERN OSCILLATION (ENSO), FERTILIZATION, NORTHERN
HEMISPHERE, RADIATIVE PROCESSES, STORMS, TEMPORAL DISTRIBUTION, TREE RINGS, VOLCANOES

37   
Dean, Caryn Lyn. 1993. Interactions Between a Tropical Mixed Boundary Layer and Cumulus Convection in a Radiative-Convective Model. M.S. Thesis, Pennsylvania State University, 159 pages.

A radiative-convective model, combining previously developed cumulus, stable cloud and radiation parameterizations with a boundary
layer scheme, was developed in the current study. The cloud model (Frank and Cohen, 1985) was modified to incorporate the effects
of both small and large clouds. The boundary layer model, adapted from a mixed layer model (Albrecht et al. 1979), was only slightly
modified to couple it with the more sophisticated cloud model. The model was tested for a variety of imposed divergence profiles,
which simulate the regions of the tropical ocean from approximately the Intertropical Convergence Zone (ITCZ) to the subtropical
high region. The sounding used to initialize the model for most of the runs is from the trade wind region of ATEX. For each
experiment, the model was run with a timestep of 300 seconds for a period of seven (7) days. The model produced an inversion height
of approximately 950 mb for each region. As the subsidence increased, typical of conditions towards the subtropical high region, the
boundary layer became moister and warmer, and the periods of deep convection became weaker and less frequent. Various cloud
spectra were also introduced into the model to test for sensitivity to the number of cloud types represented. The model produced
similar results whether one cloud or many clouds were used. However, the runs with more than one cloud generally displayed
resultant inversion heights with more stable oscillations than the equivalent runs with only one cloud type. With the exception of
higher mixing rates resulting in larger clouds, the specification of initial updraft vertical velocity and mixing rate made little difference
to the final inversion height and boundary layer thermodynamic values. Finally, sensitivity tests were done for varying sea surface
temperatures and surface wind velocities. The model responded well to changes. As sea surface temperature increased, the inversion
height increased, the boundary layer became warmer and the moisture stayed approximately the same. As surface wind velocity
increased, the inversion height decreased, and the boundary layer temperature and moisture decreased and increased, respectively. A
FGGE sounding from a region closer to the equator was tested and the results were very similar, with an inversion height near 960
mb. Therefore, the model is thought to be physically representative of the physical area described above.

Major Professor(s): Frank, William
Department: Meteorology
Principal Investigator(s): Wohlpart, A.
Program Area: Graduate Fellowships for Global Change

KEYWORDS: BOUNDARY LAYER, CLOUDS, CONVECTION, OCEANS, RADIATIVE PROCESSES, TEMPERATURE,
TROPICS, WATER VAPOR, WINDS


38   
De Bruyn, Warren J. 1994. The Heterogeneous Chemistry of Carbonyl Halides, Haloacetyl Halides and Biogenic Sulfur Species.
Ph.D. Dissertation, Boston College, 175 pages.

Heterogeneous reaction pathways involving aqueous droplets in clouds and fogs have been recognized as major mechanisms for the
chemical transformation of atmospheric trace gases. Here we examine the heterogeneous chemistry of two atmospheric systems using
a previously developed fast droplet experiment and a new bubble column apparatus. Gas-liquid uptake studies have been completed
for the following series of carbonyl and haloacetyl halides: CF3CFO, CF2O, CF3CClO, CCl2O and CCl3CClO. Some of these species
have been shown to be degradation products of hydrochlorofluorocarbons and hydrofluorocarbons which have been proposed as
substitutes for ozone depleting chlorofluorocarbons. The experiments yielded values for the product of the Henry's law coefficient (H)
and the liquid phase hydrolysis rate constant (k) in the form Hk-. Results indicate that the tropospheric removal of the degradation
products is fast enough not to contribute to the ozone depletion potential of their parent species. A series of aqueous phase uptake
studies have also been completed for key biogenic sulfur species in the marine boundary layer. Reduced sulfur species of biogenic
origin CH3SCH3, H2S, CS2, CH3SH and OCS are a major source of sulfur in the marine atmosphere. These species and their oxidation
products CH3SO3H (MSA), (CH3)2SO (DMSO), and (CH3)2SO2 (DMSO2) dominate the production of aerosol and cloud condensation
nuclei in the clean marine atmosphere. Henry's law coefficients and Sctchenow saltout coefficients have been obtained for the reduced
sulfur species and mass accommodation coefficients have been obtained for the oxidized sulfur species. The atmospheric implications
of the results have been examined. The species DMSO, DMSO2 and MSA which exhibit relatively large uptake were studied with the
fast droplet apparatus previously described in detail. The other species studies in this work exhibited uptakes too small to be measured
with the droplet apparatus. A new more sensitive bubble column apparatus was developed for the study of these molecules. In the
bubble column apparatus, a low pressure gas flow, carrying trace gas diluted in helium carrier gas, is bubbled through a liquid. The
bubbles and their transit through the liquid are carefully characterized. Measurements of gas depletion yield the desired characteristics.

Major Professor(s): Davidovits, Paul
Department: Chemistry
Principal Investigator(s): Davidovits, Paul
Program Area: Atmospheric Sciences

KEYWORDS: ATMOSPHERE, CHEMISTRY, EMISSIONS, HALOGEN SPECIES, HENRY'S LAW, HYDROLYSIS, SULFUR
SPECIES


39   
Delaney, Paul. 1991. Sensitivity of Atmospheric Radiation to Temperature, Water Vapor and Ozone Profiles. M.S. Thesis, University
of Maryland at College Park, 23 pages.

The sensitivity of the longwave spectral radiance incident on the surface to uncertainties in the measurement of temperature, water
vapor and ozone have been examined with the use of the line-by-line radiation code FASCODE2. Spectrally averaged results at one
wavenumber resolution were obtained for simulated random and systematic errors in the meteorological data under midlatitude
summer conditions. As expected, temperature errors dominate the uncertainties in the opaque regions, whereas water vapor errors
dominate the sensitivity in the atmospheric window. In general, the radiation field is most sensitive to uncertainties in water vapor,
followed by temperature, tropospheric ozone then stratospheric ozone. Systematic errors dominate radiance uncertainties, with
reasonable random errors in the meteorological data resulting in radiance errors that are of the of 0.25 to 0.5 the magnitude of the
systematic effects. The maximum effects of systematic errors on the fractional radiance error at any spectral location in the 5 to 20
micron region is the order of 2% per degree Kelvin and 1.2% per percent water vapor mixing ratio error for temperature and water
vapor uncertainties, respectively.

Major Professor(s): Ellingson, Robert G.
Department: Meteorology
Principal Investigator(s): Ellingson, Robert G.
Program Area: Quantitative Links

KEYWORDS: ABSORPTION, OZONE, RADIATIVE PROCESSES, TEMPERATURE, WATER VAPOR


40   
Detwiler, Ralph Paul. 1986. Tropical Forests and the Global Carbon Cycle. Ph.D. Thesis, Cornell University, 415 pages.

The concentration of carbon dioxide in the atmosphere has increased from 280 parts per million circa 1750 to 345 parts per million in
1984. One cause of this increase, and the principal one in recent years, has been the combustion of fossil fuels. Another has been the
destruction of forests and their replacement with agro-ecosystems, whose vegetation and soil contain much less carbon than the
vegetation and soil of undisturbed forests. In the past, the destruction of temperate forests may have contributed significantly to the
increase in atmospheric CO2. It now appears, however, that the clearing of tropical forests is the major source of CO2 from terrestrial
ecosystem. Tropical forests are cleared for shifting cultivation, permanent agriculture, pasture, and timber. These land uses differ as to
the amount of carbon stored in their vegetation and soil. To calculate the net release of CO2 from tropical forest clearing, one must
determine: (1) the rates at which tropical forests are cleared for these various uses and the rate at which cleared areas are abandoned in
shifting cultivation; (2) the carbon stored in the vegetation and soil of primary forests, logged forests, secondary forests, agricultural
fields and pastures; and (3) the fate of carbon contained in cleared vegetation and soil. These date are used in computer model that
simulates land use change in the tropics and its effects on vegetation and soil and calculates the net flux of CO2 between tropical
ecosystems and the atmosphere. The model is useful because it permits testing the sensitivity of the calculated flux to uncertainties in
the estimates of land use change, carbon storage, and the fate of cleared vegetation. The model has been used to calculate the net
release in 1980 from the vegetation of four Latin American countries and from the vegetation and soil of the entire tropics. This
research indicates that land use change in the tropics released at least 0.4 x 1015g but not more than 1.9 x 1015g of carbon in 1980,
with the more likely range being 0.4-1.6 x 1015g. Decreases in soil organic matter were responsible for 0.1-0.3 x 1015g of the release,
while the burning and decay of cleared vegetation accounted for 0.3-1.6 x 1015g.

Major Professor(s): Hall, Charles A.S.
Department: Ecology and Systematics
Principal Investigator(s): Hall, Charles A.S.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: ATMOSPHERE, CARBON CYCLE, CARBON DIOXIDE, FORESTS, LAND USE, LATIN AMERICA, MODELS,
ORGANICS, SOILS, TROPICS


41   
Deweaver, Eric. 1994. On the Dynamics of Extratropical Low-Frequency Atmospheric Variability. M.S. Thesis, University of
Maryland at College Park, 33 pages.

The discovery of El Ni¤o/Southern Oscillation (ENSO) as a dominant mode of interannual variability has lead to considerable
optimism that circulation anomalies on seasonal timescales can be predicted. On the other hand, many studies have shown that
extratropical low-frequency variability is maintained by the convergence of momentum flux by synoptic-scale eddies. Further analysis
shows that high-frequency eddies are organized and controlled by the low-frequency flow. If the low-frequency flow does exert a
dominant influence on the high-frequency eddies, it may be possible to construct a model in which the high-frequencies are
parameterized in terms of the predicted low-frequency flow. Low-frequency flow anomalies would then be directly attributable to
slowly varying boundary forcing and strictly low-frequency dynamics. This research is intended as a contribution to the goal of
constructing such a model. While our ultimate goal is to design a general low-frequency model, we have focussed on the specific case
of seasonal streamfunction anomalies associated with tropical heating events. To examine these anomalies, we have constructed a
steady-state barotropic diagnostic model. The model simulates the streamfunction anomaly between two seasons at a given level using
the observed fields of divergence and transient vorticity flux convergence for the two seasons. Because the basic state of the model is
the average of the flow for the two seasons, the model is automatically linear. Thus the global streamfunction anomaly can be thought
of as the linear sum of the streamfunction anomalies forced from various regions by various processes.

Major Professor(s): Baer, Ferdinand
Department: Meteorology
Principal Investigator(s): Baer, Ferdinand
Program Area: Computer Hardware, Advanced Mathematics, and Model Physics (CHAMMP)

KEYWORDS: ATMOSPHERE, CIRCULATION, EL NI¥O - SOUTHERN OSCILLATION (ENSO), EXTRATROPICS,
TEMPORAL DISTRIBUTION


42   
DeWitt, Craig A. 1983. Soil Moisture Stress and Nitrogen Fixation in Soybeans. M.S. Thesis, Clemson University, 70 pages.

Symbiotic nitrogen fixation in legumes is an economically important source of biological nitrogen in the food chain. The rate of
nitrogen fixation in soybean (Glycine max [L.] Merr. 'Bragg') is influenced by many environmental factors including soil water
potential. This study was conducted to determine the effects of soil moisture stress on nitrogen[C2H2]-fixation in soybeans during early
flowering. Nitrogen[C2H2]-fixation is a method of determining nitrogen fixation using the reduction of acetylene (C2H2) to ethylene in
a surrogate reaction utilizing the nitrogenase enzymes. Soybeans were grown in a Norfolk sandy loam topsoil at 27/15 C (day/night)
in a controlled environment in Soil-Plant-Atmosphere-Research (SPAR) units which were modified to permit in situ nitrogen[C2H2]-fixation measurements. At early flowering, three water stress treatments (wet soil, 0-50 kPa, and 0-100 Kpa) were imposed for a
minimum of three consecutive dry-down/recovery cycles. Nitrogen[C2H2]-fixation in soybeans during early bloom decreased during
the first dry-down cycle in each treatment. Nitrogen[C2H2]-fixation increased upon rewetting in all treatments but not to pretreatment
levels. Correlation coefficients of 0.63 and 0.58 were obtained for the first drydown in the dry and medium treatments, respectively.
No significant correlation was found for any treatment after the first dry-down period. Pod dry weight and pod nitrogen contents at
harvest were unaffected by any of the soil moisture treatments in this experiment. Total plant dry weight at harvest was 25% lower in
the 0-100 kPa treatment. The acetylene/ethylene system used in the determination of nitrogen [C2H2]-fixation proved to be nontoxic to
the plants when sampled at 3-h intervals. This system in conjunction with SPAR units allowed semi-continuous measurements of
nitrogen[C2H2]-fixation and its response to water stress in soybeans.

Major Professor(s): Lambert, Jerry R.
Department: Agricultural Engineering
Principal Investigator(s): Acock, Basil
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: ATMOSPHERE, NITROGEN CYCLE, SOILS, VEGETATION, WATER STRESS


43   
Diaz, Henry Frank. 1985. A Comparison of Twentieth Century Climatic Anomalies in Northern North America with Reconstructed
Patterns of Temperature and Precipitation Based on Pollen and Tree-Ring Data. Ph.D. Dissertation, University of Colorado, 234
pages.

The possibility of significant climatic changes over the next century of two resulting from anthropogenic modification of atmospheric
composition and vegetative alterations makes it important to determine the ranges associated with different climatic regimes that have
occurred during the present interglacial (in particular, the climate of the Middle- and Late-Holocene). The area of interest in this study
comprises northern North America going from Alaska in the west to western Greenland in the east. The approach taken in this study
was to use the modern observational record to identify the surface anomaly patterns and the associated midtropospheric circulation
features characteristic of the principal modes of interannual variance in this region. These anomaly patterns were analysed within the
context of the annual cycle by looking at seasonal variations and by comparison with the mean season-to-season changes. Principal
component analysis was one major tool used to derive objectively the characteristic anomaly fields at both the surface and upper levels
and to assess their temporal relationships. Other techniques included differencing various periods based on the integrated anomaly
field and calculating field correlations between surface temperature and 700 mb heights. The surface patterns were contrasted to those
derived using climate proxy data such as variations in tree-ring growth and fossil pollen variations in order to infer plausible circulation
regimes based on the degree of pattern similarity. Areas of consistent response during warm and/or cold periods operating at time
scales varying from years to decades to centuries and finally to the order of millennia were identified and their existence was explained
in terms of the possible redistribution (i.e. changes in the mean position and strength) of the planetary-scale waves in this region. The
finding that the zone of high amplitude response is located approximately along the mean present-day boundary between arctic and
Pacific or interior continental airstreams may help in the identification and monitoring of areas in northern North America where early
detection of climatic change due to increasing atmospheric CO2 concentration is likely. Furthermore, by relating such responses to
specific changes in the structure of the atmospheric circulation, we may have greater confidence that those surface changes are indeed
related to hemispheric-scale variations, and not to natural variability of the climate system.

Major Professor(s): Barry, Roger G.
Department: Geography
Principal Investigator(s): Diaz, Henry F.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: ATMOSPHERE, CIRCULATION, CLIMATE, HOLOCENE, NORTH AMERICA, POLLEN, PRECIPITATION,
SURFACE LAYER, TEMPERATURE, TEMPORAL DISTRIBUTION, TREE RINGS, WAVES


44   
Dietrich, William F. 1994. The Concept of Critical Levels: Should Climate Change Negotiators Use It? M.P.P. Thesis, Harvard
University, 89 pages.

Germany will host the first conference of the Parties to the United Nations Framework Convention on Climate Change. As host,
Germany is responsible for preparing background documents for use by the Parties. The German Federal Ministry for Environment,
Nature Conservation and Nuclear Safety asked researchers at the Wuppertal Institute for Climate, Environment, and Energy to serve
as the analytical round of international negotiations on climate change. This policy analysis is a background document for the
negotiations. The paper addresses the question, "What can be learned from the use of critical levels in other international
environmental negotiations that can be used in the climate change negotiations?" The paper examines the use of the critical level/load
concept in both the acid rain and stratospheric ozone negotiations, draws lessons from those experiences, and applies those lessons to
the climate change negotiations. It finds that critical levels will be useful in the climate change if environmental regulation have tended
to bring "unifactorial" explanations to bear on questions like the one asked by this study. Specifically, scholars most often employ four
different explanatory models to explain divergences in national regulatory patterns: 1) the role of domestic political institutions; 2) the
institutionalization, public trust, and political context of scientific information and advice; 3) the influence of international pressure,
regimes, and institutions; and 4) the role played by divergent cultural perceptions of risk. In this study I examine the efficacy of each of
these models in explaining the divergent regulatory histories of the two countries. I argue that, alone, none of these models is
sufficient to account for the ten-year difference in the timing of measures to combat acid rain. Only by highlighting the complicated
interplay among these factors can one illuminate the central question that guides this study. This conclusion emphasizes the power
and usefulness of multifactorial analysis.

Major Professor(s): Clark, William C.
Department: Kennedy School of Government
Principal Investigator(s): Clark, William C.
Program Area: National Institute for Global Environmental Change (NIGEC)

KEYWORDS: ACIDITY, CLIMATE, DEPOSITION, OZONE, POLICY, RISK




45   
Dignon, Jane Elizabeth. 1988. Time and Spatially Dependent Estimates of Pollutant Trace Gas Emissions and Their Effect on
Tropospheric Ozone. Ph.D. Dissertation, State University of New York at Stony Brook, 180 pages.

Statistical models have been developed to relate the rate of pollutant emissions to the rate of fuel combustion. These models have been
used to estimate global emissions of nitrogen and sulfur oxides in fossil fuel combustion since the year 1860. When averaged over the
1860 to 1980 period, global sulfur emissions increased at a rate of 2.9 percent per year, and the nitrogen emissions increased at a rate
of 3.4 percent per year. Using these statistical models along with population distribution estimates, high resolution geographical maps
of emissions can be produced for each year which fuel consumption data are available. Global emissions of NOx and SOx emissions
for 1966 and 1980 are illustrated on a latitude-longitude grid appropriate for general circulation models of the atmosphere. Emissions
of carbon monoxide from fossil fuel, wood and biomass fuel, and open burning of vegetation, as well as emissions of nitrogen and
sulfur oxides from wood and biomass fuel burning, are estimated for 1980 using emission factor methods. These trace gas sources are
also mapped globally. The impact of increasing emissions of NOx on tropospheric ozone abundance is estimated by calculations with a
one-dimensional (latitudinal) model which includes coupled tropospheric photochemistry and diffusive meridional transport. Steady-state photochemical calculations with the prescribed NOx emissions appropriate for 1966 and 1980 indicate an ozone increase of 8 to
11 percent in the Northern Hemisphere, a result which is compatible with the rise of about 12 percent between 1970 and 1981
suggested by recent observations.

Major Professor(s): Hameed, Sultan
Department: Mechanical Engineering (Atmospheric Sciences)
Principal Investigator(s): Hameed, Sultan
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: COMBUSTION, EMISSIONS, FOSSIL FUELS, SULFUR SPECIES


46   
Ding, Ming. 1992. Radiative Forcing Due to Observed Changes in Greenhouse Gases for the Period 1980-1990. M.S. Thesis, State
University of New York at Albany, 52 pages.

Recently, satellite observation of global O3 distribution for the period 1980-1990 became available. The data indicated that statistically
significant lower stratospheric O3 depletion occurred at middle to high latitudes in both hemispheres, which may perturb the radiative
forcing of the troposphere-surface climate system. Here, we study the radiative forcing due to O3 changes and compare the value with
those due to the increase in other major greenhouse gases, CO2, CH4, N2O and CFCs over the same period. In addition, we study the
direct forcing due to the CH4 increase and indirect due to increase in atmospheric O3 and stratospheric H2O associated with CH4
increase. Stratospheric O3 depletion has two compensating effects on the radiation balance at the tropopause: positive solar forcing and
negative infrared forcing. On a global mean basis, the radiative forcing due to the well-mixed greenhouse gases (CO2, CH4, N2O and
CFCs), CFCs and O3 are 0.51, 0.07, and 0.03 Wm-2, respectively. Although the forcing due to O3 depletion is comparable to that of
CFCs increase, it is small compared with the well-mixed gases. However, the calculated O3 forcing can be large on the basis of
seasons and latitudes. For example, it may reach a maximum of 0.2 Wm-2 at middle latitude summer hemisphere, which is about 50%
of the forcing due to well-mixed greenhouse gases. The results thus suggest that O3 changes can contribute significantly to the total
radiative forcing. Increase in CH4 may lead to increases in tropospheric O3 and stratospheric H2O, with subsequent effect on radiative
forcing. We find that the radiative forcing due to the stratospheric H2O increase caused by doubling the CH4 surface emission may
enhance the CH4 direct effect by more than 30%. And the CH4-induced atmospheric O3 increase may decrease the CH4 direct forcing
by 30% at middle latitude summer hemisphere, primarily caused by stratospheric O3 increase. These results suggest that indirect
forcing needs to be considered when addressing CH4 climatic effect. Finally, we carry out radiation calculations to examine the
sensitivity of the radiative forcing to the climate state and the H2O continuum treatment. The results indicate that both effects are
small, for example, about 10% when different H2O continuum schemes are used.

Major Professor(s): Wang, Wei-Chyung
Department: Atmospheric Science
Principal Investigator(s): Wang, Wei-Chyung
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: GASES, RADIATIVE PROCESSES





47   
Dippery, Joy Kirsten. 1993. Effects of Reduced and Elevated CO2 Partial Pressure on C3 and C4 Plant Growth. M.S. Thesis, Duke
University, 52 pages.

In order to study C3 and C4 plant growth in atmospheric CO2 levels ranging from Pleistocene through predicted future levels, Abutilon
theophrasti (C3) and Amaranthus retroflexus (C4) were grown in growth chambers controlled at CO2 partial pressures of 15 Pa
(approximate Pleistocene minimum), 27 Pa (preindustrial), 35 Pa (present) and 70 Pa (elevated). After 35 days of growth, CO2 had no
effect on the relative growth rate, total biomass or partitioning of biomass in the C4 species. However, the C3 species showed
increasing biomass with rising CO2 partial pressure. C3 plants grown in 15 Pa CO2 had only 8% of the total biomass of plants grown
in 35 Pa CO2. In 15 Pa CO2, C3 plants had lower relative growth rates, lower specific leaf weights and stunted reproduction relative to
plants grown in higher CO2 partial pressures. C3 plants grown in 70 Pa CO2 showed relatively greater partitioning of biomass to roots
compared with plants grown in 15 Pa CO2. This study suggests that 1) C3 species may acquire a competitive advantage over C4
species with increasing atmospheric CO2 partial pressure; 2) C4 species may have had a competitive advantage over C3 species in the
past when atmospheric CO2 partial pressure was substantially lower than current levels; 3) and supports the hypothesis that low CO2
partial pressures of the past may have been an important factor favoring the evolution of C4 species.

Major Professor(s): Strain, Boyd R.
Department: Botany
Principal Investigator(s): Strain, Boyd R.
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: BIOMASS, C3 METABOLISM, C4 METABOLISM, CARBON DIOXIDE, COMPETITION, EVOLUTION,
FERTILIZATION, GROWTH AND DEVELOPMENT, PLEISTOCENE EPOCH, PRE-INDUSTRIAL ERA, VEGETATION


48   
Dlhopolsky, Rose Marie. 1991. A Study of the Earth Radiation Budget Experiment Short Wave Measurements and Bidirectional
Reflectance Models for the Ocean Surface. Ph.D. Dissertation, State University of New York at Stony Brook, 141 pages.

Shortwave radiances from the Earth Radiation Budget Experiment (ERBE) satellites are converted to fluxes using bidirectional
reflectance models created from Nimbus 7 data. These models describe the dependence of a shortwave measurement on the angle at
which a scene is being observed and the position of the sun relative to that scene and the satellite. In this study, reflectances are
derived from Earth Radiation Budget Satellite (ERBS) shortwave radiances and sorted according to the range of angles at which they
were measured. This range is called the angular bin size. The Nimbus 7 Bidirectional Reflectance Models were created using this
same procedure. In this study, the size of the angular bins is made smaller than the sizes in the Nimbus 7 Bidirectional Reflectance
Models in order to more accurately describe the angular dependence of the shortwave reflection. Results indicate that the size of the
Nimbus 7 angular bins causes the ERBE shortwave fluxes to be overestimated when the satellite views specular reflection from the
ocean surface. This is especially severe for solar zenith angles less than 25 degrees. Clear sky shortwave radiances measured under
specular geometries are very large and are therefore not included in the processing. However, these radiances are sometimes identified
as clouds and included in the data set. This occurs because shortwave radiances reflected from clouds do not exhibit as strong a
dependence on viewing geometry as the clear sky ocean surface. Therefore, a large shortwave radiance is identified as a cloud.
Examples are given where this affects the regional data.

Major Professor(s): Cess, Robert D.
Department: Mechanical Engineering (Atmospheric Sciences)
Principal Investigator(s): Hameed, Sultan
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: MODELS, RADIATIVE PROCESSES, REFLECTANCE


49   
Donato, Timothy Francis. 1994. Radar Imaging of Oceanic Fronts at Low Grazing Angles. M.S. Thesis, North Carolina State
University, 90 pages.

Over the past twenty years imaging radars, such as Synthetic Aperture Radar and Real Aperture Radar, have seen increasing use in the
study of oceanic phenomena. The variety of ocean phenomena or features observed in radar images include (but are not limited to)
western boundary currents, shallow water bathymetric influences of the sea surface, internal wave, atmospheric boundary layer
variations, and surface wind waves. However, most of these investigations have relied on spaceborne and airborne platforms operating
at small to moderate incidence angles (Oø-60ø). Few studies have employed imaging radars operating at angles greater than 60ø
incidence or low grazing angles. In this study a Real Aperture Radar operating at low grazing angles (approximately 65ø to 87ø) is
used to identify and interpret sub-mesoscale surface features associated with oceanic fronts. To facilitate this task airborne remote
sensing and ship board sea truth activities conducted simultaneously. The research was conducted over a five day period between 1
and 5 October, 1990 off the north east coast of North Carolina. Data collection include airborne remote sensing data (radar imagery,
sea surface temperature from a radiometer, inertia navigation system data and radar altimetry), ship board sea truth (acoustic Doppler
current profiles, conductivity-temperature-depth profiles, expendable bathythermographs, radiosondes, and standard shipboard
meteorological and oceanographic observations), and ancillary sea surface temperature data from NOAA polar orbiting satellites.
Radar data was collected at a pulse repetition frequency of 100 ns and at 9.375 GHz. A total of six low resolution images were
examined and compared with sea truth for this study. The observations and results of this study show that a localized mesoscale
cyclonic flow existed within the boundary layer and is interpreted as a low level cold air advection towards the Gulf Stream. Wind
speed and air temperature remained fairly consistent over the course of the study. Wind direction, however was observed to
cyclonically rotate approximately 15ø upon crossing the Gulf Stream thermal front. This condition was a consequence of the strong
sea surface temperature gradients associated with the Gulf Stream (7øC km-1). Oceanic mixed layer measurements revealed a complex
Gulf Stream frontal region. A filament detected in sea surface temperature imagery was also apparent in the Acoustic Doppler profiles.
Two frontal regions existed as a result of the presence of this filament. One front was dominated by the thermal contrast between the
Gulf Stream and continental shelf waters. The other front was dominated by strong shears associated with the detaching filament and
the main body of the Gulf Stream. Results from this investigation demonstrate that ocean features such as thermal fronts, shear zones,
filaments, and boundary layer variations, observed in sea truth and radiometer data can be detected in low grazing angle radar images.
Azimuthal variability with respect to wind and radar look direction was apparent. The study also demonstrated that frontal features can
yield a backscatter return as high as the returns generated by hard targets, such as ships.

Major Professor(s): Morrison, J.
Department: Marine, Earth and Atmospheric Sciences
Principal Investigator(s): Pietrafesa, Leonard J.
Program Area: Marine Transport

KEYWORDS: ATMOSPHERE, BOUNDARY LAYER, CIRCULATION, CLIMATE, MARINE ENVIRONMENT, OCEANS,
REFLECTANCE, REMOTE SENSING, WINDS


50   
Donovan, Lisa Alayne. 1992. A Chrysothamnus Affair: Surviving and Developing Roots in Utah. Ph.D. Dissertation, University of
Utah, 144 pages.

Water limits plant establishment and productivity in many arid and semi-arid habitats. This study investigated patterns of water-use
characters in natural populations, and the relationships among water-use characters, growth and survival. The study concentrated on
Chrysothamnus nauseosus, commonly known as rubber rabbitbrush, and emphasized differences between juveniles (smaller
establishing plants), and adults (larger reproductively mature plants). Juveniles were found to differ from adults not only in size and
rates of mortality, but also in their water status (xylem pressure potentials), rates of gas exchange (photosynthesis and stomatal
conductance) and water-use efficiency (WUE, ratio of photosynthetic carbon gain to transpirational water loss). The differences were
due, in part, to soil moisture availability, with shallow rooted juveniles being more water stressed and more dependent on moisture
from summer rain. Summer drought resulted in high rates of seedling mortality for C. nauseosus, but larger seedlings and juveniles
were more likely to survive the drought. Though small plants were more water stress than large plants during each summer, they had
lower WUE throughout the season, based on measurements of instantaneous gas exchanges and of leaf carbon isotope discrimination
( ). This negative relationship between   and plant size in the natural population, as well as temporal shifts in   found under
controlled environment conditions, suggested that there was a developmental component to variation in WUE in addition to
environmentally induced variation. Quantitative genetic analysis indicated that there was also genetic variation for  , though the
estimates were relatively low, and hence some potential for genetic differentiation in   in response to natural selection. For C.
nauseosus, lower WUE (higher  ) was not necessarily associated with greater biomass accumulation and growth,and both
photosynthetic capacity and stomatal limitation appeared to contribute to the variation in the relationship between   and growth.
Though there were stable differences between juveniles and adults for water-use characters, and in particular WUE, the functional
significance of these differences remains unknown.

Major Professor(s): Ehleringer, James R.
Department: Biology
Principal Investigator(s): Ehleringer, James R.
Program Area: Ecosystems Function and Response

KEYWORDS: CARBON CYCLE, DESERTS, GENETICS, GROWTH AND DEVELOPMENT, LEAVES, MORTALITY,
PHOTOSYNTHESIS, PRECIPITATION, SOILS, TEMPORAL DISTRIBUTION, VEGETATION, WATER STRESS, WATER USE


51   
Duda, David P. 1994. Macrophysical and Microphysical Influences on Radiative Transfer in Two Dimensional Marine Stratus.
Ph.D. Dissertation, Colorado State University, 202 pages.

Recent estimates of the effects of increasing amounts of anthropogenic sulfate aerosol on global climate have indicated that its impact
on the radiative forcing of the atmosphere may be comparable in magnitude to the effect from increases in CO2. Much of this impact
is expected from the indirect effects of the aerosol on global cloud microphysics and the subsequent impact on cloud albedo. However,
internal horizontal variations in cloud optical properties are also known to affect cloud albedo and reflectance, and thus affect the
remote sensing of cloud microphysics. A broadband solar radiative transfer model (SHSG) capable of simulating the radiances and
fluxes in a medium that varies both vertically and horizontally was used to quantify the effects of both cloud microphysical changes
and cloud inhomogeneity changes on the radiative properties of marine stratus. Two dimensional cross sections of cloud physics data
taken from a set of three dimensional RAMS/LES simulations of marine stratus provided realistic optical property data for radiative
transfer simulations. Along with a control run using typical marine CCN concentrations, two studies using enhanced concentrations of
CCN were examined. The results of the radiative transfer calculations indicated that in unbroken marine stratus clouds the net
horizontal transport of photons over a domain of a few km was nearly zero, and the domain average broadband albedo computed in a
two dimensional cross section was nearly identical to the domain average calculated from a series of independent pixel approximation
(IPA) calculations of the same cross section. This matches the findings from Cahalan et al. (1994) for monochromatic calculations in
a simple cloud model, and suggests that accurate computations of domain averaged albedo in unbroken marine stratus can be made
using IPA calculations with one dimensional radiative transfer models.

Major Professor(s): Stephens, Graeme L.
Department: Atmospheric Science
Principal Investigator(s): Stephens, Graeme L.
Program Area: National Institute for Global Environmental Change (NIGEC)

KEYWORDS: CLOUDS, MARINE ENVIRONMENT, MICROPHYSICS, RADIATIVE PROCESSES, REFLECTANCE, REMOTE
SENSING


52   
Dugue, Charles Pierre Michel. 1989. Colloidal Behavior in Natural Waters as Described by Ultrafiltration. M.S. Thesis, Illinois
Institute of Technology, 52 pages.

The properties of colloidal substances and their possible correlation with other materials present in the natural waters help explain their
movement in the environment. Ultrafiltration using hollow fiber filters was used to separate colloids from natural water into different
size fractions. These size fractions were used in competitive binding experiments with a trace metal (yttrium) and a suspended solid
(silica gel). The distribution coefficient of the metal between the suspended solid and the colloidal organics was found to be linearly
related to the amount of organic in solution. This relationship was found to be strongly influenced by solution pH, the nature of the
suspended solids as well as the amount of other natural cations present in the system.

Major Professor(s): Holsen, Thomas M.
Department: Environmental Engineering
Principal Investigator(s): Gaffney, Jeffrey S., and Nancy A. Marley
Program Area: Terrestrial Transport

KEYWORDS: COLLOIDS, FULVIC ACIDS, HUMIC ACIDS, WATER QUALITY


53   
Dutton, Todd H. 1994. The Effects of Temperature, Atmospheric CO2 Concentrations and Arbuscular Mycorrhizal Populations
from Two Disparate Biomes on Growth and Biomass Accumulation of 'Eureka' Lemon (Citrus limon (Hort.)). M.S. Thesis, Arizona
State University, 38 pages.

Growth and biomass accumulation of rooted Citrus limon Hort. 'Eureka" cuttings, after inoculation with either arbuscular mycorrhizal
fungal populations originating from a plains grassland or Sonoran desertscrub biome, were measured after 3 months of growth in
factorial combinations of near-optimal (29.4 C day max/21.1 C night min.) or supraoptimal (40.5 C day max./32.2 C night min.)
diurnal temperature cycles and ambient (350-380 æmol mol-1) or enriched (650 æmol mol-1) atmospheric CO2 concentrations. Shoot
growth and root to shoot ratio were affected by an interaction of temperature and CO2 treatments. Supraoptimal temperatures
suppressed shoot extension growth and leaf accumulation; however, this heat-induced growth suppression was alleviated by a near
doubling of atmospheric CO2. At near-optimal temperatures, shoot growth of CO2-enriched trees and those grown under ambient CO2
condition was similar. At near-optimal temperatures, root to shoot ratio was less for CO2-enrichment trees compared with trees grown
at ambient CO2. Conversely, root to shoot ratio at supraoptimal temperatures of CO2-enriched and trees grown under ambient CO2
conditions was similar. Temperature was the sole factor affecting mycorrhizal colonization of 'Eureka' lemon tree roots. Supraoptimal
temperatures decreased total root colonization but increased arbuscular colonization relative to near-optimal temperatures. Shoot and
root growth were also affected by an interaction of temperature and different ecotype populations of arbuscular mycorrhizal fungi. At
near-optimal temperatures, lemon tree leaf area to root length ratio was not affected by mycorrhizal treatments, but at supraoptimal
temperatures, there was a 37% greater leaf area to root length ratio in trees inoculated with the plains grassland population of AM
fungi compared with those trees inoculated with the Sonoran desertscrub population of AM fungi. These data suggest that benefits of
the mycorrhizal symbiosis may not necessarily be based on growth enhancement of the host plant.

Major Professor(s): Martin, Chris
Department: Botany
Principal Investigator(s): Acock, Basil, Leon H. Allen, Jr., and Bruce A. Kimball
Program Area: Carbon, Climate, and Vegetation

KEYWORDS: CARBON DIOXIDE, CLIMATE, FUNGI, GROWTH AN