Investigating Relations Between Satellite Derived Land Surface Parameters and Meteorological Variables

Abstract

The importance of mapping, monitoring and quantifying changes in eco‐physical and agro‐hydrological environments has received greater attention by scientific community in the study of global change. Land Surface Temperature (LST) and its relation with Normalized Difference Vegetation Index (NDVI) can be used to map continuous fields of physical surface characteristics such as surface soil and near surface air temperature on a regional scale. The present study was aimed to model temporal evolution of LST and its relation with NDVI and ground temperatures during rabi crop growing season over semi‐arid to arid Gujarat region, India. The estimated LSTs were regressed against NDVI for assessing dynamic response of Surface Temperature / Vegetation Index for different districts in Gujarat. The result shows that a strong dynamic negative correlation exists between land surface temperature and NDVI. The steepness of slope of LST/NDVI relation was found less during mid growth stages (i.e. peak vegetative period) compared to early and maturity stages of rabi crop growing season. Scatterogram of Banaskantha district over different dates depicts the narrower spread during vegetative growth period than early and late growth stages. However, width and spread of scatterogram during peak vegetative growth period (i.e. January) vary among districts in response to vegetation cover and hydric deficits. A good agreement was observed between satellite retrieved surface temperature with ground estimates of mid day surface soil temperature and near surface air temperatures. The result show that average bias in retrieved surface temperature compared with ground based surface soil temperatures observations over three meteorological stations is approximately 2°C or less for four dates of satellite over pass. The results again confirm that mid day near surface air temperature is easier to model in period of good vegetation cover when extreme temperatures are not present and no important hydric deficit exists.