Abstract
Abstract. 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 stand-alone column radiation transport model coupled with the Mie, T-matrix and geometric optics 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 shortwave instantaneous dust direct radiative forcing was studied for a range of aerosol and surface characteristics representative of 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.
Highlights
Mineral dust is an important and integral part of the Earth system
We discuss clear-sky radiative transfer calculations conducted for different locations over the Arabian Peninsula and the sensitivity studies
In each case mineral dust direct radiative forcing (DRF) is calculated as a difference between perturbed (P) and control (C) experiments, where P experiments account for dust aerosol and C experiments do not
Summary
Mineral dust is an important and integral part of the Earth system. Dust aerosol perturbs radiation balance by changing optical properties of the atmosphere (Claquin et al, 2011; Sokolik and Toon, 1999; Myhre et al, 2013). The Arabian Peninsula is the third largest source region of dust after North Africa and Central and East Asia, accounting for about 12 % of total emissions (Tanaka and Chiba, 2006) This region has received little attention so far; it is lacking field campaigns and has few in situ observations. The current study aims at better quantification of the clearsky mineral dust instantaneous direct radiative forcing (DRF) and its diurnal cycle over the Arabian Peninsula. This region is less studied and lacks in situ observations, even though it represents one of the major sources of dust and occupies a significant part of the dust belt area (Prospero et al, 2002).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
