A New Approach for Satellite Monitoring of Pan-Arctic Terrestrial CO 2 Exchange
NASA Terrestrial Ecology program
John Kimball, Kyle McDonald and Eni Njoku (CalTech), Steve Running (UMT), Walt Oechel (SDSU)
We are developing a new satellite-based approach for regional assessment and monitoring of terrestrial net carbon exchange (NEE) for the pan-Arctic; NEE quantifies the magnitude and direction of land-atmosphere net CO2 exchange and is a fundamental measure of the balance between carbon uptake by vegetation net primary production (NPP) and carbon loss through soil heterotrophic respiration (R h). We are using satellite microwave remote sensing to extract surface soil wetness and temperature information with existing satellite-based measurements of vegetation structure (LAI, FPAR) and productivity (GPP, NPP) from Aqua/Terra MODIS sensors to derive spatially explicit estimates of NEE for the pan-Arctic at weekly and annual intervals. Calibration and validation activities involve multiscale comparisons with tundra CO2 eddy-flux tower and biophysical measurement networks, detailed hydroecological process model simulations and low altitude flux aircraft overflights along regional moisture and temperature gradients across Alaska. This project provides the first-ever operational satellite-based approach for regional assessment and monitoring of NEE, the primary measure of carbon exchange between the land and atmosphere. These data also provide a valuable new tool for assessing regional patterns, temporal variability and environmental controls on pan-Arctic terrestrial sources and sinks for atmospheric CO2 and advances our understanding of the extent to which the Arctic is being affected by recent warming trends and reinforcing global change.
Heinsch, F.A., M. Zhao, S.W. Running, J.S. Kimball, R.R. Nemani, et al., 2006. Evaluation of remote sensing based terrestrial productivity from MODIS using regional tower eddy flux network observations. IEEE Transactions in Geoscience and Remote Sensing (In press).
Kang, S., S.W. Running, M. Zhao, J.S. Kimball, and J. Glassy, 2005. Improving continuity of MODIS terrestrial photosynthesis products using an interpolation scheme for cloudy pixels. International Journal of Remote Sensing 26(6), 1659-1676.
., K.C. McDonald, and M. Zhao, 2006. Spring thaw and its effect on terrestrial vegetation productivity in the western Arctic observed from satellite microwave and optical remote sensing. Earth Interactions (In press).