Estimation of air temperature using the temperature/vegetation index approach over Andhra Pradesh and Karnataka

One of the critical variables characterizing the energy and water cycle at the earth’s surface is near-surface air temperature. This has massive significance in agrometeorological applications aimed at achieving sustainable agriculture. Remote sensing data can solve this problem both globally and regionally, particularly with non-weather station areas. This study investigated the temperature vegetation index (TVX) approach’s applicability to estimate air temperature at a satellite overpass in Andhra Pradesh and Karnataka. Land surface temperature (LST) and surface reflectance products on an 8-day composite basis from MODIS were used for selected days in 2008. The TVX method used for a 9 × 9 moving window and the respective intercept and slope relation between the normalized difference vegetation index (NDVI) and the LST were obtained. Thus, the relation was extrapolated to the maximum NDVI (NDVImax) received for this window to calculate the air temperature. Validation was performed over observations from four automatic weather stations (AWS). The overall results for the mapping of instantaneous air temperature were satisfactory for the Julian days corresponding to three months, i.e., February, September, and October, due to adequate vegetation cover. An overall comparison of observed and calculated values identified a root mean square error (RMSE) of 1.1 °C.