Influence of dust source databases on the simulated radiation budget and sea breezes along the Arabian Peninsula

Dust aerosols may be lofted from dry surface soils/deserts into the atmosphere by mechanical means associated with strong surface winds. Intense dust lofting events can substantially impact visibility and the atmospheric radiation budget due to absorption and scattering of radiation by dust particles. Dust-induced changes to insolation and surface thermal emission can impact the column radiative heating rates and net column radiative flux. This, in turn, impacts temperature profiles and the development and intensity of atmospheric phenomena that are initiated by daytime heating. As such, numerical model prediction of dust episodes in dust prone areas relies upon robust dust lofting parameterizations and erodible fraction datasets that best simulate the amount and location of lofted dust.

In this study, we have examined the dust lofting capabilities of three methods of specifying dust erodible fraction: (1) idealized lofting of dust wherever bare soil exists, (2) application of a 1-deg resolution dust erodible fraction dataset (Ginoux et al. 2001, JGR), and (3) application of a 1-km resolution dust lofting location dataset (Walker et al. 2009, JGR). In each methodology, dust lofting is a function of threshold friction velocity and soil moisture. We will present results from simulations at 2km grid spacing that were performed for a dust lofting event that occurred over the Arabian Peninsula from Aug 3-5, 2016. The various lofting methods result in large differences in the mass of dust that is lofted from the surface and transported throughout the region. The variability in lofted dust impacts the AOD, insolation, net radiative flux and heating rates, and thus, the surface fluxes and sea-breeze development, which then subsequently impacts additional dust lofting. Implications for future representation of dust processes in mesoscale, regional and climate models will be presented.