Land Surface Temperature Measurements from EOS MODIS Data

The global land-surface temperature (LST) and normalized difference vegetation index (NDVI) products retrieved fromModerate Resolution Imaging Spectroradiometer (MODIS) data in 2001 were used in this study. The yearly peak valuesof NDVI data at 5km grids were used to define six NDVI peak zones from -0.2 to 1 in steps of 0.2, and the monthlyNDVI values at each grid were sorted in decreasing order, resulting in 12 layers of NDVI images for each of the NDVIpeak zones. The mean and standard deviation of daytime LSTs and day-night LST differences at the grids correspondingto the first layer of NDVI images characterize the thermal status of terrestrial ecosystems in the NDVI peak zones. Forthe ecosystems in the 0.8-1 NDVI peak zone, daytime LSTs distribute from 0-35 °C and day-night LST differencesdistribute from -2 to 22 °C. The daytime LSTs and day-night LST differences corresponding to the remaining layers ofNDVI images show that the growth of vegetation is limited at low and high LSTs. LSTs and NDVI may be used tomonitor photosynthetic activity and drought, as shown in their applications to a flood-irrigated grassland in Californiaand an unirrigated grassland in Nevada.