HR: 11:35h
AN: B52B-06    [Abstracts]
TI: Regional Ecosystem Carbon Exchange in the Southern Great Plains: Measurements, Modeling, and Scaling
AU: Torn, M S
EM: mstorn@lbl.gov
AF: Earth Sciences Division, Mail Stop 90-1116 Lawrence Berkeley National Lab 1 Cyclotron Rd, Berkeley, CA 94720, United States
AU: * Riley, W J
EM: wjriley@lbl.gov
AF: Earth Sciences Division, Mail Stop 90-1116 Lawrence Berkeley National Lab 1 Cyclotron Rd, Berkeley, CA 94720, United States
AU: Biraud, S C
EM: scbiraud@lbl.gov
AF: Earth Sciences Division, Mail Stop 90-1116 Lawrence Berkeley National Lab 1 Cyclotron Rd, Berkeley, CA 94720, United States
AU: Fischer, M L
EM: mlfischer@lbl.gov
AF: EETD, Lawrence Berkeley National Lab Mail stop 90K-125 1 Cyclotron Rd, Berkeley, CA 94720, United States
AU: Billesbach, D S
EM: dbillesbach1@unl.edu
AF: University of Nebraska-Lincoln, 25 LW Chase Hall Biological Systems Engineering Dept, Lincoln, NE 68588, United States
AU: Berry, J A
EM: joeberry@stanford.edu
AF: Carnegie Institution and Stanford University, 260 Panama St, Stanford, CA 94305, United States
AB: The extremely heterogeneous landscape of the ARM (Atmospheric Radiation Measurement) Climate Research Facility (ACRF) in the U.S. Southern Great Plains is representative of the southern boundary of the NACP Midwest intensive experiment. The area is largely agricultural with vegetation cover type and status that vary on sub- kilometer scales. In this study we developed, applied, and tested a "bottom- up" approach to inferring terrestrial C exchanges at fine scales (down to 250 m). Measurements at the ACRF include a 60 m tower instrumented with eddy covariance (ECOR) systems at several heights, about 20 permanent ECOR towers, several portable ECOR systems, many atmospheric and cloud sensing systems, and regular balloon sonde and aircraft measurements. We applied the land-surface model ISOLSM (with recent modifications to the plant physiological submodel) forced with OK and KS Mesonet climate datasets and MODIS vegetation indices. A method to infer vegetation cover type using satellite data and archetypal LAI annual profiles was developed and successfully tested against USDA census data for the region. The model's net CO₂ exchange estimates were calibrated and tested using eddy correlation data from the dominant surface covers. Three years spanning a substantial precipitation gradient (2003 - 2005) were then simulated. Large differences in annual regional CO₂ exchanges were predicted corresponding to expected system responses to available moisture. Spatial scaling analysis from 250 m to 100 km indicated that homogenizing LAI and vegetation cover can impact annual NEE substantially, including changing the region from a predicted net CO₂ source to a net sink. Further, differences in NEE associated with spatial scaling differed between years, indicating that accurate bottom-up NEE estimates in this heterogeneous region require fine-scale analysis approaches.
DE: 0402 Agricultural systems
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0438 Diel, seasonal, and annual cycles (4227)
DE: 0466 Modeling
SC: Biogeosciences [B]
MN: 2007 Fall Meeting