Utilization of MATLAB to Realize LST Retrieval and Thematic Mapping from FY-3/MERSI Data

Abstract

Currently,application-oriented researches on the data of Medium Resolution Spectral Imager(MERSI),which is on board China's new generation polar orbit meteorological satellite FY-3,are very insufficient,due to the reason that the data as a new source have been delivered only since 2008.With the normal operation of FY-3 satellite system,it is necessary to develop an operational module for FY-3/MERSI regional land surface temperature(LST) retrieval and its post-processing,since LST is required for a wide variety of scientific studies but FY-3/MERSI's operational LST products have not yet been provided by National Satellite Meteorological Center(NSMC).Based on an analysis of FY-3/MERSI L1 data's HDF5 format and its channel characteristics,the authors selected the generalized single-channel algorithm developed by Jimenez-Mu n～oz Sobrino to directly realize the LST retrieval at 250 m spatial resolution with MATLAB programming and the thematic mapping of LST derivative products.This paper describes the parametric processes of LST retrieval algorithm in detail,which include radiometric calibration,cloud detection,estimation of two intermediate parameters-surface emissivity and atmospheric water vapor,and calculation of thermal indexes from LST.On these bases,an automatic flowchart for FY-3/MERSI LST retrieval and thematic mapping was established.Experimental results of this flowchart applied in Shanghai thermal environmental monitoring show that it can process FY-3/MERSI L1 data in a fast,real-time and automatic way,thus suitable for operational products producing and sharing,with the saving of human resources.It is also proved that FY-3/MERSI data and various forms of LST products can reveal the spatial pattern of Shanghai thermal field and the urban heat island effect more finely and intuitively.