Satellites Observation over the Marseille-berre Area, during the Ubl/clu- Escompte Experiment

Remote sensing observations over the Marseille-Berre area were analyzed as part of the UBL/CLU ESCOMPTE experiment conducted in Marseille (France) in 2001. One hundred and fifty nine NOAA-AVHRR images, with a 1 km spatial resolution, were extracted over the period of June 4 to July 13 2001. Land Surface Temperatures (LST) and a fractional vegetation index were derived from the images. The temporal resolution of up to six images a day allows the study of LST diurnal variations and the construction of statistical averages. LST variations of up to 8 C were observed between the rural and the urban-industrial areas of Marseille and Marignane. Highest LST closely follows the contours of densely built or industrial districts. Urban parks generates cool islands of 1.5 to 3.5 C. This cooling effect is confirmed by the significant negative correlation between the afternoon LST and the fractional vegetation index. An EOS-ASTER image, with a high spatial resolution of 15 to 90 m, is being analyzed in an attempt to document the emissivities of urban surfaces, which are critical in deriving accurate LST and in studying the surface energy exchange. Results of remote sensed land surface temperatures are interpreted as a function: of a land cover classification from a multi spectral SPOT image; and of surface and atmospheric measurements from the ESCOMPTE experiment.