Retrieval of geophysical parameters from Moderate Resolution Imaging Spectroradiometer thermal infrared data: Evaluation of a two-step physical algorithm

A two-step physical algorithm that simultaneously retrieves geophysical par ameters from Moderate Resolution Imaging Spectroradiometer (MODIS) measurem ents was developed. The retrieved geophysical parameters include atmospheri c temperature-humidity profile, surface skin temperature, and two surface e missivities within the shortwave (3-5-mu m) and the longwave (8-14.5-mu m) regions. The physical retrieval is accomplished in two steps: (i) The Tikho nov regularization method is employed to generate a regularization solution along with an optimum regularization parameter; (ii) the nonlinear Newtoni an iteration algorithm is carried out with the regularization solution as a first-guess profile to obtain a final maximum probability solution for geo physical parameters. The algorithm was tested with both simulated and real MODIS Airborne Simulator (MAS) data. Sensitivity studies on simulated MAS d ata demonstrate that simultaneous retrievals of land and atmospheric parame ters improve the accuracy of the retrieved geophysical parameters. Finally, analysis and accuracy of retrievals from real MAS data are discussed. (C) 2000 Optical Society of America. OCIS codes: 280.0280, 030.5620.