Retrieval of Stratospheric Aerosol Properties from SCIAMACHY Limb Observations
Dörner, Steffen; Kühl, Sven; Pukite, Janis; Penning De Vries, Marloes; Wagner, Thomas
Max Planck Institute for Chemistry, GERMANY
Since the start of the Stratospheric Aerosol Measurement program in 1975 satellites have improved
our understanding of the global distribution of clouds and aerosols. Observations in occultation and
limb geometry contain information on profiles of different types of particles in the stratosphere (i.e.
aerosols and clouds), which have an important influence on the global radiation budget (e.g. after
strong volcanic eruptions) and stratospheric ozone chemistry (e.g. heterogeneous chemistry inside
the polar vortex).
The Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) on ENVISAT provided measurements in limb geometry for almost ten years between 2002 and 2012. Its vertical resolution of 3.3 km at the tangent point and the broad spectral range (UV/VIS/NIR) allow (besides retrievals of trace gas profiles) to retrieve profile information of stratospheric aerosol properties. Due to the long light path through the atmosphere this instrument is sensitive to optically thin layers of stratospheric aerosol like the Junge Layer. We present a new technique to retrieve aerosol extinction profiles using the Monte Carlo Atmospheric Radiative Transfer Inversion Model (McArtim). Our technique is based on an Onion-Peeling approach: Starting at a reference tangent height the aerosol extinction is varied for each subsequent tangent height until the simulated intensity profile is in agreement with the measurement. The retrieval of the extinction profile is performed at several wavelengths separately, allowing us to estimate particle sizes based on the Angstrom coefficient. Results from our method will be compared to existing satellite and ground based measurements.