The aerosol direct effect on climate through absorption and reflection of sunlight, and the aerosol indirect effect through modification of cloud microphysics, onset of precipitation and cloud reflectance, depend on knowledge of the vertical distribution of the aerosol in relation to the altitude of the cloud layers. The A-train with Calipso measurements of the aerosol vertical distribution, Cloudsat measurements of the cloud profiles and MODIS, OMI, PARASOL detailed passive measurements of aerosol and clouds from the UV to the IR generates a unique opportunity of producing data sets that can help understand better the aerosol effect on clouds and climate and reduce the uncertainties in climate change predictions.
Inversion of the CALIOP spectral lidar data to obtain the vertical distribution of the aerosol and their properties is presently based on assumed aerosol backscattering ratios, a quantity with uncertainty of factor 2. We developed an inversion scheme that constrains the lidar inversion over water using MODIS data [Kaufman et al., 2003 a, b; Leon et al 2003], producing independent fine and coarse aerosol profiles without assuming a specific backscattering ratio, increasing the accuracy to the well validated MODIS aerosol optical thickness (AOT) derivation over the oceans of �0.03�0.05AOT. Here we propose to further improve the MODIS-CALIOP joint inversion over the oceans, test its performance and produce a high quality climatology of aerosol and cloud profiles over the oceans that will be then used to study the direct and indirect aerosol forcing of climate.
Specifically we plan to:
- Improve the MODIS-lidar inversion scheme to account for nonspherical particles phase function by using the lidar depolarization, and constraining the aerosol properties using PARASOL information on the refractive index and the size of the fine mode. On the East part of PARASOL images, where the CALIOP measurements will be performed, the geometrical conditions are optimum to confirm the presence of non-spherical particles.
- Generate regional statistics of the fraction and properties of aerosol located above, in and under the cloud layers, with an accuracy of ~30% better than from CALIPSO alone.
- Validate the derived profiles using aircraft lidar and in situ measurements and the column fine and coarse aerosol using AERONET data.
- Study the impact of aerosol and cloud vertical distribution on the direct effect on climate of aerosols under and above the clouds.
- Measure the aerosol indirect and semi direct effects using the inverted CALIOP data, MODIS aerosol and cloud microphysics and CLOUDSAT cloud vertical profiles.
Yoram J. Kaufman, Richard Ferrare and J.-F. Leon are seeking membership in the CALIPSO science team. Didier Tanr� and Jacques Pelon are French members of the Science team and are seeking continuation of their membership. The work proposed is new and is not included in the Kaufman IDS investigation.
