New Numeric Data Packages from CDIAC

Tropical Africa: Land Use, Biomass, and Carbon Estimates for 1980

NDP-055, ORNL/CDIAC-92 (1996)

The maximum potential aboveground biomass, land use, and estimated biomass and carbon data of Tropical Africa are given for 1980, and a method is presented for extending this data set to 1990 and beyond based on population and land-cover data. The biomass data and carbon estimates are for woody vegetation in Tropical Africa. These data were collected to reduce the uncertainty in historical releases of carbon from land-use change. The data cover 22.7 × 10⁶ km² of the Earth's surface and include those countries that, for the most part, are located in Tropical Africa. Maximum-potential-biomass and land-cover information (but not biomass or carbon estimates) are given for countries bordering the Mediterranean Sea and in southern Africa (i.e., Egypt, Libya, Tunisia, Algeria, Morocco, South Africa, Lesotho, Swaziland, and Western Sahara).

The database was developed with the GRID module in the ARC/INFO^® geographic information system. Source data were obtained from the United Nations Food and Agriculture Organization (FAO), the U.S. National Geophysical Data Center, and a limited number of biomass-carbon-density case studies. These data were used to derive the maximum potential and actual (ca. 1980) aboveground biomass-carbon values at regional and country levels. The land-use data provided were derived from a vegetation map originally produced for the FAO by the International Institute of Vegetation Mapping, Toulouse, France.

Analyses conducted with this database found that 18% of Tropical Africa was in closed forest and 36% was in open forest in 1980. These forested lands contained more than 138 × 10⁹ Mg of aboveground live biomass, equivalent to 69 × 10⁹ Mg of carbon. Closed forests and open forests had mean aboveground biomass values of 209 Mg/ha and 67 Mg/ha, respectively. These values are down from maximum potential aboveground live biomass values of 296 Mg/ha for closed forest and 108 Mg/ha for open forest.

The NDP consists of 26 digital files, including 7 ARC/INFO^® export files, 8 flat ASCII data files, 10 FORTRAN and SAS^® data-retrieval files, and 1 documentation file that explains the contents and format of each data file. The package totals 250 MB of data and is available on 8-mm and 0.25-in. QIC tapes.

Tropical Africa's potential biomass density (top) vs its
actual biomass density of more than 100 Mg/ha.

Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Meteor Cruise 18/1 in the North Atlantic Ocean (WOCE Section AIE, September 1991)

K. M. Johnson and D. W. R. Wallace, Brookhaven National Laboratory, Upton, New York
B. Schneider, Institut für Ostseeforschung, Rostock-Warnemunde, Germany
L. Mintrop, Institut für Meereskunde, Kiel, Germany
Compiler: Alex Kozyr, CDIAC

NDP-056, ORNL/CDIAC-91 (1996)

The North Atlantic Ocean has an intense meridional circulation cell that carries near-surface waters from the tropics northward and deep arctic waters southward. At high latitudes, the water cools and sinks in a process called "overturning." The overturning rate (and thus the intensity of the meridional transports of mass, heat, and salt) is an important control parameter in modeling the ocean's role in climate. A series of cruises were made from March 1991 through 1995 to gather the data needed to study the overturning of the North Atlantic. This NDP presents the data recorded during one of those cruises. Starting in Reykjavik, Iceland, and ending in Hamburg, Germany, the cruise measured total carbon dioxide (TCO₂) and total alkalinity (TALK) at hydrographic stations and partial pressure of CO₂ (pCO₂) while under way. It also measured pressure, temperature, salinity, and oxygen measured with a conductivity, temperature, and depth (CTD) sensor; bottle salinity; oxygen; phosphate; nitrate; nitrite; and silicate. These measurements were made with 61 CTD casts, including 59 bottle casts and 2 calibration stations. Replicate samples from seven Niskin bottles at five stations were also collected. TCO₂ was measured with an automated sample processor (that extracted CO₂ from seawater samples) coupled to a coulometer (that detected the extracted gas). The precision and accuracy of the system was ±1.60 mol/kg. Samples collected for TALK were measured with standard potentiometric techniques; precision was ±2.0 mol/kg. Under-way pCO₂ was measured by infrared photometry; precision was ±2 atm.

The NDP consists of three oceanographic data files, three FORTRAN-77 data-retrieval files, and a readme file and requires 420 kB of disk space. It is available along with its full documentation on the CDIAC World Wide Web home page.

Sea-surface temperature and pCO₂ measured during the R/V Meteor Cruise 18/1.

Carbon-14 Measurements in Atmospheric CO₂ from Northern and Southern Hemisphere Sites, 1962-1993

Reidar Nydal and Knut Lövseth, Norwegian Institute of Technology, Trondheim, Norway
Compiler: Tom Boden, CDIAC

NDP-057, ORNL/CDIAC-93 (1996)

In the 1960s, thermonuclear bomb tests released significant pulses of radioactive ¹⁴C into the atmosphere. This major perturbation allowed scientists to study the dynamics of the global carbon cycle by measuring and observing rates of isotopic exchange. The Radiological Dating Laboratory at the Norwegian Institute of Technology performed ¹⁴C measurements in atmospheric CO₂ from 1962 to 1993 at a network of ground stations in the northern and southern hemispheres. These measurements were supplemented during 1965 with high-altitude (9- to 12.6-km) air samples collected with aircraft of the Norwegian Air Force. The resulting database, coupled with other ¹⁴C data sets, provides a greater understanding of the dynamic carbon reservoir and a crude picture of anomalous sources and sinks at different latitudes. This database is outstanding for its inclusion of early ¹⁴C measurements, broad spatial coverage of sampling, consistency of sampling method, and ¹⁴C calculations corrected for isotopic fractionation and radioactive decay.

Fourteen stations from Spitsbergen (78°N) to Madagascar (21°S) were used. Some of the stations have data for only a brief period, while others have measurements through 1993. Sampling stations subject to local industrial CO₂ contamination were avoided. The sites have sufficient separation to describe the latitudinal distribution of ¹⁴C in atmospheric models. All the surface ¹⁴C measurements consisted of quantitative absorption of atmospheric CO₂ in carbonate-free 0.5-N NaOH solution. The ¹⁴C measurements were made in a CO₂ proportional counter and calculated as per mil excess above the normal ¹⁴C level defined by the U.S. National Institute of Standards and Technology (NIST). Atmospheric ¹⁴C content is finally expressed as ¹⁴C, which is the relative deviation of the measured ¹⁴C activity from the NIST oxalic acid standard activity after correction for isotopic fractionation and radioactive decay related to age. The data are organized by sampling station, and each record of the database contains the sampling dates, values for ¹⁴C excess (¹⁴C) relative to the NIST standard, fractionation ¹³C (¹³C) relative to the Pee Dee Belemnite standard, corrected ¹⁴C (¹⁴C) excess, and the standard deviation for ¹⁴C.

The ¹⁴C station data show a sharp increase in tropospheric radiocarbon levels in the early 1960s and then a decline after the majority of nuclear tests came to an end on August 5, 1963. The sharp peaks in tropospheric radiocarbon in the early 1960s are more pronounced in the Northern Hemisphere, reflecting the location of most atomic-weapon tests. The measurements show large seasonal variations in the ¹⁴C level during the early 1960s, mainly as a result of springtime transport of bomb ¹⁴C from the stratosphere. During the 1970s, the seasonal variations are smaller and caused partly by seasonal variations in CO₂ from fossil-fuel emissions. The rate of decrease of atmospheric radiocarbon provides a check on the exchange constants of the atmosphere and ocean.

The NDP consists of 21 data files totaling 0.2 MB and is available on 9-track and 8-mm tapes and on floppy diskettes. Along with its documentation, it is also available on CDIAC's World Wide Web home page.

Daily Snow-Depth Measurements from 195 Stations in the United States

D. R. Easterling, P. Jamason, D. Bowman, P. Y. Hughes, and E. H. Mason, National Climatic Data Center, Asheville, North Carolina
Compiler: Linda Allison, CDIAC

NDP-059, ORNL/CDIAC-95 (1996)

The National Climatic Data Center (NCDC) has collected and made available daily measurements of snow depth at 195 National Weather Service (NWS) first-order climatological stations in the United States. The 195 stations encompass 388 unique sampling locations in 48 of the 50 states; no observations from Delaware or Hawaii are included in the database. The database covers from 1893 to 1992; however, not all station records span the complete period. Ideally, a station record should contain daily data for at least the seven winter months (January through April and October through December), but not all stations have data for all these months. Each record in the database contains one station's daily data values for onemonth, including data source, measurement, and quality flags. The snow-depth data have undergone extensive manual and automated quality-assurance checks by NCDC and CDIAC. These reviews involved examining the data for completeness, reasonableness, and accuracy and included comparison of some data records with records in NCDC's Summary of the Day-First Order database.

The NDP consists of 12 data files that are available via CDIAC's anonymous file transfer protocol (ftp) service, via the World Wide Web, and on 8-mm and 0.25-in. QIC tapes and on floppy diskettes. The database is about 79,000 kB.

Daily snow depth for 1945 (solid line) and 1985 (dashed) for
Mount Washington in New Hampshire.

Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Thomas Washington Cruise TUNES-3 in the Equatorial Pacific Ocean (WOCE Section P16C)

Catherine Goyet, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
Peter R. Guenther, Charles D. Keeling, and Lynne D. Talley, Scripps Institution of Oceanography, La Jolla, California
Compiler: Alex Kozyr, CDIAC

NDP-060, ORNL/CDIAC-96 (1996)

The largest oceanographic experiment ever attempted is the World Ocean Circulation Experiment (WOCE), a major component of the World Climate Research Program. WOCE cruises (through 1998) will measure the global, spatial, and temporal distributions of TCO₂ and other carbon-related parameters. The goal of the CO₂ survey includes estimation of the meridional transport of inorganic carbon in the Pacific Ocean in a manner analogous to the oceanic heat transport, evaluation of the exchange of CO₂ between the atmosphere and the ocean, and preparation of a database suitable for carbon-cycle modeling and the subsequent assessment of the anthropogenic CO₂ increase in the oceans. The final data set is expected to cover about 23,000 stations.

This NDP presents CO₂-related measurements obtained during the 31-day Leg 3 of the Research Vessel Thomas Washington TUNES Expedition (TUNES-3) along the WOCE zonal Section P16C, which is located in the equatorial part of the Pacific Ocean along the 150¯W meridian, between 17.5°S and 19.0°N. The cruise began in Papeete, Tahiti, on August 31, 1991, and finished in Honolulu, Hawaii, on October 1, 1991. All 105 hydrographic and 8 large-volume stations were completed to the full water-column depth. Station spacing was 30 nautical miles, except between 3°N and 3°S, where it was 10 nautical miles. Measurements made included pressure, temperature, salinity, and oxygen measured by conductivity, temperature, and depth sensor; and bottle salinity, oxygen, phosphate, nitrate, nitrite, silicate, CFC-11, CFC-12, TCO₂, and TALK. In addition, potential temperatures were calculated from the measured variables.

The TCO₂ concentration in 652 seawater samples was determined by semiautomated coulometry. The precision of these measurements was estimated to be better than 0.01%. The desired accuracy was better than 4 mol/kg. The TALK concentration in 539 seawater samples was determined by a potentiometric acid-titration system; 71 samples were collected for later shore-based reference analyses of TCO₂ and TALK by vacuum extraction and manometry.

The NDP consists of two FORTRAN 77 data-retrieval-routine files a documentation file, and two oceanographic-data files. The data are available on 9-track, 8-mm, and 0.25-in. tapes and on floppy diskettes. Along with its documentation, the NDP is also available on CDIAC's World Wide Web home page.

Distribution of the total CO₂ in mol/kg from
WOCE Section P16C along (roughly) 150°W.