Land surface temperature estimation and evapotranspiration modelling from satellite derived parameters at high resolution

Abstract

All features on the earth surface with temperature greater than zero Kelvin, newlinewill emit radiation primarily in the longwave infrared (LWIR) portion (8 14 and#956;m) newlineof the electromagnetic spectrum. Sensing this radiated energy to estimate the newlinetemperature of the land surface is the basis of thermal infrared (TIR) remote newlinesensing (RS) and the temperature thus estimated is known commonly as Land newlineSurface Temperature (LST). newlineRetrieval of LST from TIR RS images is not a trivial task especially for newlinesensors with only one band in the LWIR window (e.g. Landsat series of satellites). newlineThe major difficulty in the retrieval of LST is the need for information about the newlinesurface emissivity. Majority of the earth s surface will not emit radiation with newlinemaximum efficiency as defined by the laws of thermodynamics and will have newlineemissivity less than one. In addition, the emissivity will vary with the bandwidth newlineof observation. Emissivity is often estimated using a vegetation indices based newlinemethod with Normalized Difference Vegetation Index (NDVI) being traditionally newlineused for the purpose. newlineOne of the major applications of the remotely sensed LST data is the newlinemodelling of evapotranspiration (ET) and several models have been developed for newlinethe estimation of ET using LST data. One class of RS based ET models is the newlinesurface energy balance (SEB) based models that utilize this LST data for ET newlinemodelling. The SEB models can be further classified into single pixel models and newlinecontextual models. The single pixel models require ground observations of newlinemeteorological and vegetation information whereas, the contextual models can newlinework with RS inputs alone. Hence, for countries such as India where there is a newlinescarcity of regular ground observations, contextual models might be a better choice newlinefor modelling ET. newline