Liu, Xue (George Mason University, MS 5C3, Center for Earth Observing and Space Research, Fairfax, VA, 22030-4444; Phone: 703-993-4045; Email: xliu4@gmu.edu)

Changes of Carbon Sink in Terrestrial Vegetation?

X. Liu*, M. Kafatos

It has been evidenced that the Earth’s terrestrial biosphere, particularly the forests in the Northern Hemisphere, is responsible at least partially for the “missing” carbon sink in the global carbon cycle system. However, how this terrestrial sink will change over time with changing climate and atmospheric CO2 concentrations is unsolved. Undoubtedly, understanding the dynamics of this terrestrial sink is of critical importance to global carbon cycle modeling, future projections of atmospheric CO2 concentration in turn climate change, and decision-making regarding terrestrial carbon sequestration. While in situ flux measurements can provide high temporal resolution analysis and insights to involving processes, it is difficult to extrapolate to large spatial scales. At the continental to global scales, usage of satellite remote sensing data is inevitable. We, in this paper, present results from our preliminary study on this problem using satellite remote sensing data. Based on the 20 years time series of normalized difference vegetation index (NDVI) produced by NOAA AVHRR system during its continuous land observing missions from 1981 to 2001, global land cover classification, and the strong correlation between NDVI and NPP, the changes of carbon sink in the terrestrial vegetation have been analyzed, including the trends and strengths. In addition, the causes to these changes have also been analyzed with regarding to climate and atmospheric CO2 concentration variations.