This website describes the SODA project ( Synergized Optical Depth of Aerosols ) and its related products.

The aim of this algorithm is to retrieve the aerosols optical depth over the ocean based on a combination of CALIPSO's CALIOP, CLOUDSAT's CPR and AMSRE measurements. The original version was developed by Damien Josset in the frame of the CALIPSO mission (CNES support). The product result from the cooperation between IPSL-LATMOS, NASA-LaRC and ICARE data center.

After an intercalibration of the RADAR/LIDAR signals on clear sky scenes over the ocean and an accurate correction of water vapor attenuation of the radar signal, the aerosol optical depths are computed for non-cloudy air columns. As the RADAR signal is not significantly modified by aerosols layers but the LIDAR signal is attenuated, the modification of the relationship between their cross sections compared to non-cloudy scenes are only due to the transmission by aerosols. The related aerosol optical depth is then deduced from the ratio of the lidar and radar surface cross-sections.

SODA Mean Aerosol Optical Depth for August 2008 at 532nm
SODA Mean Aerosol Optical Depth for 2008/08 at 532nm

Generated Products

3 products are currently available :

  • SODA : the base one. It contains the retrieved optical depths at the CALIOP basic horizontal resolution of 333m
  • SODA_5km : this product should be the most straightforward to use. It is a 5km averaged SODA product centered on CALIOP 5km footprints. It discriminates the aerosol and cloud scenes using the CALIOP layers mask
  • SODA_5km_L3_OD : it is a monthly average of the 5km SODA product on a 2.5 by 2.5 degree map