Retrieval of composition and size distribution of stratospheric aerosols with the SAGE II satellite experiment.

Abstract

The SAGE II satellite system was launched on October 5, 1984. It has seven radiometric channels and is beginning to provide water vapour, NO SUB 2 and O SUB 3 concentration profiles and aerosol extinction profiles at a minimum of three wavelengths. In preparation for the use of these data and assuming the aerosol size distribution is lognormal, a parametric study was conducted on the effect of size distribution parameters and composition of stratospheric aerosols on the expected extinction in the aerosol and water vapour channels. Calculated results show that aerosol characteristics can be retrieved from the SAGE II data set assuming stratospheric aerosols are distributed lognormally. A simple, fast and operational method of retrieving characteristics of stratospheric aerosols from the water vapour and three wavelength aerosol extinction profiles is proposed. Some examples are given to show the practicality of the scheme. Possible sources of error for the retrieved values and the limitation of the proposed method are discussed. This method may also prove applicable to the study of aerosol characteristics in other multispectral extinction measurements. (A)