PARENT SESSION
Friday, August 11, 8:00-10:30 am
Poster Session 26 - Latebreaking and newsworthy posters
Exhibit Hall, Ballroom Level, Cook Convention Center

Scaling up of carbon exchange dynamics from AmeriFlux sites to a super-region in eastern North America.

Schmid, HaPe¹, Wayson, Craig^*,1, Katul, Gaby², Oren, Ram², Novick, Kim², Post, Mac³, Rahman, Faiz¹, Sims, Dan⁴, ¹ Indiana University, Bloomington, Indiana² Duke University, Durham, North Carolina³ Oak Ridge National Laboratory, Oak Ridge, Tennessee⁴ Ball State University, Muncie, Indiana

ABSTRACT- We present preliminary results of a strategy to use in-situ observations from 40 AmeriFlux sites in eastern North America to scale up carbon exchange dynamics to a large region of North America (4x10⁶ km²) in a variety of climatic and landuse settings. The strategy uses measured fluxes of CO₂, energy, water, and other biophysical and biometric parameters to train and calibrate surface-vegetation-atmosphere models, along with satellite derived drivers. The flux footprint function indicates the time-varying surface "field-of-view" of an eddy-flux sensor. For each observation period, the modeled flux footprint window is overlaid with a high resolution vegetation index map to determine a footprint-weighted vegetation index for which the observation is representative. To achieve matching of measured and modeled fluxes, the ecosystem parameters of the models are adjusted to those contained in the dynamically variable flux-tower footprints. Calibrated models are used in conjunction with MODIS data, atmospheric re-analysis data, and digital land-cover databases to derive ecosystem exchange fluxes over the study domain. For two preliminary sites, one with homogeneous land cover and one with heterogeneous land cover, both show a general match in trend when comparing in-situ flux measures with modeled results. However, the heterogeneous site comparison exhibits a very large scatter around this trend indicating the need to integrate across spatial and temporal scales better before producing an estimate of annual net ecosystem exchange (NEE) for the entire domain.

Key words: carbon flux, net ecosystem exchange, AmeriFlux