Variability of stratospheric aerosol size distribution parameters between 2002 and 2005 from measurements with SAGE III/M3M

Abstract. Stratospheric aerosol size distribution parameters are derived from the solar occultation data of the SAGE III/M3M instrument and their evolution between 2002 and 2005 is shown. The broad wavelength spectrum of the measurements allows for the retrieval of all parameters controlling the assumed monomodal lognormal size distribution. Besides including periods with very close to background conditions, there were three smaller tropical eruptions during the SAGE III/M3M mission. After the Ruang, Reventador and Manam eruptions a reduction in average aerosol size and an increase in number density was observed. Apart from the likely effect of the eruptions on the particle size distribution (PSD), an influence of seasonal polar winter condensation events including meteoric smoke particles on the retrieved aerosol size is possible, especially due to the longlasting low stratospheric temperatures during the northern winters of 2002/2003 and 2004/2005. During the same winters, polar stratospheric clouds (PSCs) were likely observed by the instrument. A comparison of the stratospheric aerosol size retrieval data set with balloon-borne in situ measurements in Kiruna, Sweden, shows generally good agreement, but there are systematic differences between in situ and satellite retrievals below roughly 15 km altitude. Finally, the effect of the necessary assumption of a PSD shape on the aerosol size retrieval with remote sensing instruments is shown and discussed.