Author:
Sanghavi S.,Martonchik J. V.,Landgraf J.,Platt U.
Abstract
Abstract. The vertical profiles of aerosol often provide a clear picture of transport processes, and are an indicator of elevated secondary aerosol formation or primary aerosol sources close to the surface. The vertical extent of clouds and aerosols also governs the sign and magnitude of their net radiative forcing. Ground- and satellite-based lidar measurements presently provide much of this information, however their sampling of 3-D data is limited due to infrequent, sparce or uneven coverage. From a remote-sensing perspective, retrievals of many trace-gases suffer from uncertainties due to aerosol and would benefit from co-located information on the amount and vertical distribution of aerosol loading. This motivates the development of complementary methods to retrieve vertical information on aerosols using satellite data, which have the advantage of more frequent global coverage. SCIAMACHY onboard ENVISAT provides spectral data at moderate resolution in the UV/VIS including the O2 A- and B-bands, which contain vertical information due to the known vertical profile of O2. We make combined use of these bands in an optimal estimation based algorithm applicable both over bright and dark surfaces to retrieve the parametrized vertical profile of aerosol, in addition to the optical thickness from SCIAMACHY data. We present a case study over Kanpur, India, showing good agreement with coincident AERONET data, capturing seasonal cycles and a periodic wind-blown dust event over Kanpur.