Stratospheric aerosol extinction profile retrievals from SCIAMACHY limb-scatter observations

Abstract

This dissertation presents a method for retrieving stratospheric aerosol extinction profiles from a global satellite data set. Ten years of limb radiance measurements with the instrument SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard the European environmental research satellite Envisat provides the unique opportunity to derive a stratospheric aerosol extinction data set over a long time period (2002 2012) with a good global coverage on a daily basis. Stratospheric sulfate aerosols have a significant impact on climate but the determination is still subject to large uncertainties. To improve our understanding of climate relevant processes an accurate determination of stratospheric aerosol properties is crucial. Deriving stratospheric aerosol extinction from limb radiance spectra requires complicated radiative transfer calculations. An algorithm based on a color-index approach combining normalized limb radiance spectra at 470 and 750 nm is applied to retrieve aerosol extinction profiles between 12 and 35 km altitude. A Mie phase function for typical background aerosols is implemented. The resulting SCIAMACHY stratospheric aerosol data set can serve as a foundation for climatological interpretation with respect to natural variability and anthropogenic impact.