Retrieval of aerosol properties above liquid clouds from POLDER/PARASOL measurements (Invited)
Abstract
Most of the current aerosol retrievals from passive sensors are restricted to cloud-free scenes, which strongly reduce our ability to monitor the aerosol properties at a global scale. When a high loading of strong absorbing aerosols is present above clouds, a rather strong positive radiative forcing is expected (warming) as well as significant biases on the retrieved cloud properties. The presence of aerosol layers above liquid clouds may also affect the dynamical evolution of clouds. The monitoring of multi-layer scenes at global scale is therefore of importance for climate study. The presence of Aerosols Above Clouds (AAC) affects the polarized light reflected by the cloud layer, as shown by the spaceborne measurements provided by the POlarization and Directionality of Earth Reflectances (POLDER) instrument. POLDER measurements combined with collocated and simultaneous information about clouds from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument paved the way for the development of a retrieval technique of AAC properties on the global scale. In a first part, we will recall the theoretical basis of the method and present a sensitivity study analysis that evaluates the contribution of the POLDER polarized measurements for the simultaneous retrieval of the aerosol and clouds properties. In a second part, we will present the seasonal and spatial variability of the AAC properties retrieved for one year of data. Finally, an estimation of the impact of aerosols above cloud will be presented for a case study, in terms of both radiative forcing and cloud retrieved parameters biases.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A54A..05W
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE Aerosols and particles;
- 0321 ATMOSPHERIC COMPOSITION AND STRUCTURE Cloud/radiation interaction