Aerosol vertical profile measurements using passive radiometric measurements

Aerosol vertical profiles in the lowest 1-2 km of the atmosphere are not very well studied due to technology limitations (e.g. LIDARs) and air space restrictions (e.g. manned and unmanned aircrafts). This study investigates sensitivity of the radiance measurements in UV-VIS part of the spectrum to the aerosol profiles from the standard columnar almucantar and direct sun measurements combined with low elevation sky scanning (from the horizon to zenith direction).

GRASP algorithm is used to simulate scattered sky radiances and conduct aerosol profile inversions. Radiance measurements are conducted by the sun-sky radiometer at subset of standard AERONET wavelengths (340, 380, 440, 500, 675, 870). AErosol RObotic NETwork (AERONET) is a network of sun-sky-moon photometers that measure solar radiation at 9 wavelength bands (centered at 340, 380, 440, 500, 675, 870, 937, 1020, 1640 nm, 2-25 nm FWHM filter transmission). The main AERONET products are columnar aerosol optical depth, Angstrom exponent (from direct sun measurements), single scattering albedo and size distribution (from Almucantar and hybrid scans). The additional products investigated in this study are volume density and aerosol extinction coefficient profiles. This study evaluates CIMEL 318T pointing accuracy (near horizon), effect of surface albedo on the inversions and ability of radiance measurements to invert vertical profiles both from synthetic and real measurements at 2 locations: Greenbelt, MD and Rotterdam, NL.