ROSA Working Package 2

Solar occultation measurements are known to provide highly accurate observations of stratospheric aerosol extinction at different wavelengths, because they do not require a priori knowledge of the aerosol particle size distribution, phase function or aerosol composition, in contrast to the limb-scatter retrieval.
In order to substantially improve SCIAMACHYs limb-scatter aerosol product the following tasks are required to complete this work package:

WP 2.1 Application of the aerosol particle size retrieval developed in WP 1 to multi-wavelength extinction profile retrievals from SCIAMACHY limb-scatter observations. This needs to be done in an iterative process, because the extinction profile retrievals from limb-scatter observations require a priori knowledge on the scattering phase function, i.e., indirectly knowledge of the particle size distribution.

WP 2.2 Investigation of the sensitivity of the retrieved particle size information (from both occultation and limb measurements) and aerosol extinction profiles (from limb measurements) on the assumed refractive index. Depending on the source of the aerosols (volcanic, background) its composition and consequently refractive index will differ. The effect on aerosol retrievals is poorly understood.