Vegetation response to climate variability in India from 2001 to 2010

Food supply in India is a critical issue in sustaining a large population, and more accurate predictability of agricultural productivity is necessary for policy makers. After the Green revolution, the productivity in India has increased dramatically, but the leveling-off of the productivity was expected in the near future. Decreasing of ground water was already observed and some climate models predict a higher frequency of drought in the 21st century. For a better understanding of vegetation response to climate change, we analyzed the satellite images of India from 2001 to 2010. MODIS satellite imagery shows high spatial variability in vegetation indices in response to climate variability. In this study we scrutinize the cause and mechanism of the spatial variability in vegetation growth in India. First, we tried to find the corresponding climate variability from re-analysis data (MERRA and NCEP-NCAR reanalysis data) and satellite imagery such as TRMM, GIMMS, and MODIS, as well as interpolated climate observation data (CRU). Although the precipitation variability due to ENSO has the strongest impact on vegetation growth, the other climate variability, such as shortwave radiation, also perturbed the vegetation response to climate changes. Second, we proved our hypothesis explaining the vegetation growth trend by running the Terrestrial Observation and Prediction System (TOPS) model. The model results were compared with satellite images and showed reasonable spatial pattern of net primary production to explain the observed vegetation growth variability to climate change. Those results can contribute to a more profound understanding of the mechanism of vegetation growth in India toward future prediction in food supply.