2^nd Annual AmeriFlux Meeting

St. Louis, MO October 28-29 1997

Day 1

Following a brief introduction by Dave Hollinger, eighteen groups presented

site/research summaries. The following sites were represented:

Michigan/UMBS - Chris Vogel, (Teeri)

Indiana - Hans Peter Schmid, N. Shurpali, (S.Grimmond)

Smithsonian (Maryland)- Jess Parker

Oregon - Michael Unsworth

Florida - Ken Clark, Henry Gholz

Duke - Gabriel Katul

Wisconsin (WLEF tower) - Peter Bakwin, Ken Davis

Niwot Ridge (CO) -Andrew Turnipseed, Dave Bowling, (Russ Monson)

La Selva (Costa Rica) - Hank Loescher, (Oberbauer)

Oak Ridge (TN) - Dennis Baldocchi

Wind River Crane Site (WA) - Kyaw Tha Paw U

Wyoming - Bill Massman

Kansas (grassland) - Marv Wesely

U-pad; Barrow (Alaska)/chaparral(California) - Rommel Zulueta, (Walt Oechel)

Harvard Forest (MA)/Thompson (Manitoba)- Bill Munger, (Steve Wofsy)

Nebraska (grassland) - Shashi Verma

Harvard Forest (MA) - Ricardo Sakai, (David Fitzjarald), (Kathleen Moore)

Howland (Maine)/USFS - Dave Hollinger, Kevin Tu

Jerry Elwood (DOE) outlined objectives for AmeriFlux, emphasizing the importance of research in C flux, storage and sequestration. Specific objectives were stressed, namely to define the magnitude and variation in NEP for major ecosystem types, identify the controls on NEP (i.e. biology/ecology, meteorology/climate, land use/site history) and provide data for evaluation of models and remote sensing techniques. Priorities for AmeriFlux were also highlighted. These included, in addition to getting all sites running, the need for rigorous QA/QC, process studies to facilitate interpretation of the flux data, archiving of the data, and the definition of specific scientific questions to be addressed by the network. Several questions were raised for the network to address, namely 1) why a network as opposed to independent sites; 2) how representative are sites/how to determine representativeness; 3) how to scale fluxes; 4) what benefits are to be gained from measurements of stable isotope ratios at the sites; 5) how can the flux data be linked with global/inverse modeling approaches; and 6) what other measurements are important or would provide value-added benefits to the network.

The importance of the network was reemphasized by Diane Wickland (NASA) for the evaluation of remote sensing data and algorithms in light of the upcoming launches of several EOS satellites in 1998.

The future of the AmeriFlux calibration/intercomparison procedures was discussed by Dave Hollinger. The suggestion was made for each site to use a platinum resistance thermometer for reliable and accurate (±0.05%) temperature measurements. Early intercomparison results indicate significant discrepancies among temperature measurements. A pt-100 system with a 4-wire signal conditioner (w/voltage output) can be obtained at a reasonable cost (several hundred dollars - contact D. Hollinger for more info). The net radiometer used in the intercomparisons was questioned. Marv Wesely, Shashi Verma (chair), and Kyaw Tha Paw U formed a "Measurements group" to advise on alternatives. In addition, work is underway to provide each site with two high precision CO₂ standards for better calibration and intercomparison of the gas analyzers than currently provided by off-the-shelf standards. This would also alleviate the problems of shipping calibration gases around with Bob Evans and the AmeriFlux "gold standard" system. The possibility of a second "gold standard" system was also mentioned. This second system could be shipped to a site and set up and run by the site personal at their convenience (and when the weather was suitable).

Dennis Baldocchi reviewed FLUXNET - the "network of networks". As with AmeriFlux, FLUXNET would provide a central data archive site, ensure QA/QC, provide inter-calibration for intercomparibility (i.e. between AmeriFlux and EUROFLUX) and provide value-added products for model testing, data interpretation and model development. It was noted that most of the major ecosystem types were represented by AmeriFlux, EUROFLUX, OZ Flux and LBA with the exception of savannas (Africa).

Jess Parker introduced the International Canopy Crane Network (ICCN) - a network of crane sites around the world. Currently, there are 4 sites in operation and 3 are proposed for the future. Two sites currently operate eddy flux instrumentation.

Jim Ehleringer discussed the use of stable isotopes (¹³C, ¹⁸O) for constraining carbon cycling at ecosystem to global scales. The potential for discerning the contribution of C3 vs. C4 pathways (¹³C), aboveground vs. belowground (¹⁸O) as well as seasonal changes in physiology was emphasized (¹³C and ¹⁸O). In addition, the potential for making long-term or IFC-based isotope along with eddy flux measurements within the AmeriFlux network was addressed.

Bill Massman briefly discussed some recent work on diffusivities of various gases (H₂ O, CO₂, CH₄, CO, O₃, SO₂, NH₃, N₂O, NO, NO₂, O₂, N₂). As these may be useful for various eddy flux applications, a table will be provided by Bill for the AmeriFlux web page.

Issues of data archiving were discussed by Bill Munger and Antoinette Brenkert. Harvard no longer encrypts posted data files but requires adherence a "fair use" policy. This fair use policy was modified and adopted as the AmeriFlux FAIR USE POLICY. Agreement was reached to make all data available at CDIAC within a reasonable time frame -- at all times subject to fair use. Several, including K.T. Paw U and Shashi Verma, expressed concern that the release of data too soon may not allow graduate students under disparate and somewhat independent schedules fair and reasonable opportunity for publication. Others expressed their willingness to release their data as they process it which, among other reasons, could facilitate modeling and intercomparison. It was finally agreed that as a target, all data will be made available at CDIAC within TWO YEARS of measurement subject at all times to the FAIR USE POLICY and with special consideration to situations involving, for example, graduate students. Joe Berry proposed that a continuous record of meteorological data from each site be made available sooner to facilitate model development and application. Others, including Peter Bakwin, felt a continuous record would involve too much work by each site. A decision was ultimately reached that each site provide meteorological data as per METEOROLOGY CORE MEASUREMENTS (IV.A. in Science Plan) as soon as possible including references to alternative sources (e.g. NCDC) for filling gaps in the data. A "data group" consisting of Bill Munger, Dennis Baldocchi, Joe Berry and Antoinette was formed to advise Antoinette Brenkert on details of implementing the AmeriFlux data system.

Dave Hollinger led a review of the AmeriFlux Science Plan. Criticisms and suggestions included, among others, changing the focus from "national" to "the Americas", moving atmospheric N deposition from core to desired measurements (Henry Gholz) and moving aerodynamic roughness and zero plane displacement from vegetation to meteorological measurements (K.T. Paw U). The Science Plan was subsequently put to vote and accepted contingent upon revision for syntax and grammar.

Due to the case sensitive nature of world wide web searches and variation in the capitalization of "AmeriFlux" (e.g. "Ameriflux" vs. "AmeriFlux" vs. "AMERIFLUX"), Hollinger made a proposal to standardize the official spelling of "AmeriFlux" to one of the 3 alternatives. This issue was put to a vote and the majority (17 to 13) chose to adopt "AmeriFlux" as the official capitalization of the name of the network. All references to the network should appear as AmeriFlux.