Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula

Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula

Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula
S. Osipov, G. Stenchikov, H. Brindley, and J. Banks
Atmos. Chem. Phys. Discuss., 15, 12301-12352, (2015)
S. Osipov, G. Stenchikov, H. Brindley, and J. Banks
Diurnal cycle, Dust forcing, Arabian Peninsula
2015
In this study we attempted to better quantify radiative effects of dust over the Arabian Peninsula and their dependence on input parameters. For this purpose we have developed a standalone column radiation transport model coupled with the Mie calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments were carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18–20 March 2012. Comprehensive ground-based observations and satellite retrievals were used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing were estimated both from the model and observations. Diurnal cycle of the the shortwave instantaneous dust direct radiative forcing was studied for a range of aerosol and surface characteristics representative for the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing were evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions, along with anisotropic aerosol scattering, are mostly responsible for diurnal effects.



DOI: 10.5194/acpd-15-12301-2015