LAND SURFACE TEMPERATURE RETRIEVAL IN WETLANDS USING NORMALIZED DIFFERENCE VEGETATION INDEX-EMISSIVITY ESTIMATION AND ASTER EMISSIVITY PRODUCT

摘要

Land Surface Temperature (LST) has the potential to actrnas a continuous indicator of the ecological status ofrnwetlands. Accurate emissivity values are required inrnorder to calculate precise LST. We test two emissivityrnretrieval methods and their influence on LST calculatedrnfrom a Landsat 7 image of a highly dynamic wetland inrnSouthern Spain. LST calculated using NDVIrn(Normalized Difference Vegetation Index) thresholdrnestimations and the ASTER emissivity product arerncompared. The results show differences of around 0-1 Krnfor most land covers, and up to 3 K for areas of bare soilrnwhen Landsat and ASTER images have the samernacquisition date. Tests using Landsat and ASTERrnimages from different seasons do not show greaterrndifferences between both LSTs. This has importantrnimplications for automated LST retrieval methods, suchrnas the one planed by the USGS using Landsat andrnASTER emissivity products.