Estimating minimum and maximum air temperature using MODIS data over Indo-Gangetic Plain

Spatially distributed air temperature data are required for climatological, hydrological and environmental studies. However, high spatial distribution patterns of air temperature are not available from meteorological stations due to its sparse network. The objective of this study was to estimate high spatial resolution minimum air temperature (Tmin) and maximum air temperature (Tmax) over the Indo-Gangetic Plain using Moderate Resolution Imaging Spectroradiometer (MODIS) data and India Meteorological Department (IMD) ground station data. Tmin was estimated by establishing an empirical relationship between IMD Tmin and night-time MODIS Land Surface Temperature (Ts). While, Tmax was estimated using the Temperature-Vegetation Index (TVX) approach. The TVX approach is based on the linear relationship between Ts and Normalized Difference Vegetation Index (NDVI) data where Tmax is estimated by extrapolating the NDVI-Ts regression line to maximum value of NDVImax for effective full vegetation cover. The present study also proposed a methodology to estimate NDVImax using IMD measured Tmax for the Indo-Gangetic Plain. Comparison of MODIS estimated Tmin with IMD measured Tmin showed mean absolute error (MAE) of 1.73°C and a root mean square error (RMSE) of 2.2°C. Analysis in the study for Tmax estimation showed that calibrated NDVImax performed well, with the MAE of 1.79°C and RMSE of 2.16°C.