Simultaneous Retrieval of Diurnal to Seasonal Surface Temperatures and Emissivities over SGP ARM–CART Site Using GOES Split Window

Abstract

GOES-8 thermal infrared split window measurements have been used with a simultaneous land surface temperature (LST)?spectral emissivity retrieval algorithm to examine the potential of a combined retrieval methodology cast into a variational solution for temperatures at multiple but short-term 6- to 24-h time intervals and emissivities at multiple spectral bands assumed to be invariant over the selected time intervals. Retrieved LST and emissivity quantities under differing atmospheric conditions over an annual cycle are validated and analyzed in regard to their underlying diurnal and seasonal variations over the Department of Energy?s Atmospheric Radiation Measurement?Cloud and Radiation Test Bed (ARM?CART) site in Kansas and Oklahoma. It is shown that the accuracy of the retrieval algorithm depends primarily on GOES infrared channel detector noise and uncertainties in columnar water vapor path, in which retrieval accuracy increases as pathlength decreases. A detailed analysis is given of the characteristic temporal?spatial gradient structures of LSTs and emissivities over the ARM?CART domain at point to area space scales and diurnally to seasonally varying timescales. Emphasis is given to explaining the relationship of heterogeneous features in the retrievals in conjunction with physical attributes of the landscape, that is, ecotones and phenology, and the effects of prior cloudiness on subsequent LSTs.