Case Studies of Aerosol Retrievals over the Ocean from Multiangle, Multispectral Photopolarimetric Remote Sensing Data

Abstract

To evaluate the global effects of aerosols on the direct radiative balance, tropospheric chemistry, and cloud properties of the earth’s atmosphere requires high-precision remote sensing that is sensitive to the aerosol optical thickness, size distribution, refractive index, and number density. This study uses the multiangle 0.41-, 0.55-, 0.865-, and 2.25-mm channel data from the airborne Research Scanning Polarimeter to retrieve aerosol properties over the Pacific Ocean. It is shown that such photopolarimetric data are highly sensitive to the size distribution and refractive index of aerosol particles, which reduces the nonuniqueness in aerosol retrievals using such data as compared with less comprehensive datasets. Moreover, it is found that polarized reflectances obtained at the shorter wavelengths (0.41 and 0.55 mm) are significantly less sensitive to the contribution of the ocean’s upwelling light than total reflectance measurements, providing a natural tool for the separation between the estimation of oceanic and atmospheric scattering properties.