François-Marie Bréon

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Aerosol concentration and cloud droplet radii derived from space-borne measurements are used to explore the effect of aerosols on cloud microphysics. Cloud droplet size is found to be largest (14 micrometers) over remote tropical oceans and smallest (6 micrometers) over highly polluted continental areas. Small droplets are also present in clouds downwind of(More)
Urban heat island is among the most evident aspects of human impacts on the earth system. Here we assess the diurnal and seasonal variation of surface urban heat island intensity (SUHII) defined as the surface temperature difference between urban area and suburban area measured from the MODIS. Differences in SUHII are analyzed across 419 global big cities,(More)
Ocean color sensors enable a quasi-permanent monitoring of the chlorophyll a concentration, Chl a, in surface waters. This ubiquitous photosynthetic pigment cannot, however, be used to distinguish between phytoplankton species. Distinguishing phytoplankton groups from space is nevertheless necessary to better study some biochemical processes such as carbon(More)
We propose a new method for the estimation and the correction of directional effect on satellite derived surface reflectance time series. The correction assumes that the shape of the Bidirectional Reflectance Distribution Function (BRDF) varies much more slowly than the reflectance magnitude. The BRDF shape is quantified by two parameters R and V which(More)
For better knowledge of the carbon cycle, there is a need for spaceborne measurements of atmospheric CO2 concentration. Because the gradients are relatively small, the accuracy requirements are better than 1%. We analyze the feasibility of a CO2-weighted-column estimate, using the differential absorption technique, from high-resolution spectroscopic(More)
Two months of spaceborne POLDER polarization measurements have been used to generate empirical surface bidirectional polarization distribution functions (BPDF’s). Eleven surface classes have been defined based on a surface classification and a vegetation index. Within each class, the surface polarized reflectance was found rather homogeneous. The surface(More)
The POLDER instrument on board ADEOS provides the first opportunity to apply the two-channel ratio technique in the near infrared to retrieve atmospheric water vapor content at the global scale. Over land, POLDER estimates compare well with radiosonde measurements, with a 3.1-kg m 2 rms error. There is a clear negative bias of a few kg m 2 however. This(More)