Retrieval of stratospheric background aerosol scattering coefficient from twilight polarization measurements

A backward Monte Carlo computation procedure has been used to simulate the intensity and degree of polarization of the twilight sky during 1977. It was found that the single scattering approximation is applicable for detection of stratospheric aerosols by twilight measurement during background periods. Based on the simulation, a scheme is proposed for retrieving the stratospheric aerosol scattering coefficient utilizing the measured degree of polarization at the 0.7-microm wavelength in the zenith direction of the twilight sky. Compared with the in situ measurement, both the retrieved total optical depth and the retrieved profile of the aerosol scattering coefficient below 30 km agree reasonably well with measurements.