Investigation of Dust-Induced Direct Radiative Forcing Over the Arabian Peninsula Based on High-Resolution WRF-Chem Simulations

This study investigates the impact of dust on radiation over the Arabian Peninsula (AP) during the reported high, low, and normal dust seasons (March-August) of 2012, 2014, and 2015, respectively. Simulations were performed using the Weather Research and Forecasting model coupled to a Chemistry module (WRF-Chem). The simulated seasonal horizontal and vertical dust concentrations, and their interannual distinctions, match well with those from two ground-based AERONET observations, and measurements from MODIS and CALIOP satellites. The maximum dust concentrations over the dust-source regions in the southern AP reach vertically upto 700 hPa during the high dust season, but only upto 900-950 hPa during the low/normal dust seasons. Stronger incoming low-level winds along the southern Red Sea and those from Iraq bring in higher-than-normal dust during the high dust summers. We conducted a sensitivity experiment by switching-off the dust module to assess the radiative perturbations due to dust. The results suggest that active dust-module improved the fidelity of simulated radiation fluxes distributions at the surface and top of the atmosphere vis-& agrave;-vis Clouds and the Earth's Radiant Energy System (CERES) measurements. Dust results in a 26 Wm-2 short-wave (SW) radiative forcing in the tropospheric-column over the AP. The SW radiative forcing increases by another 6-8 Wm-2 during the high dust season due to the increased number of extreme dust days, which also amplifies atmospheric heating. During extreme dust days, the heating rate exhibits a dipolar structure, with cooling over the Iraq region and warming of 40%-60% over the southern-AP. Dust is the dominant tropospheric aerosol in the Arabian Peninsula (AP). High dust loading and prolonged episodes are crucial in dust-radiation feedback mechanisms. WRF-Chem successfully simulated the spatial distribution of dust aerosols and their underlying dust-transport mechanisms over the study region. Model results reveal that dust aerosols influence surface and atmospheric radiation, resulting in cooling at the surface and warming in the overlying atmosphere. Extreme dust days exhibit significant heating in the south and cooling in the north. This study enhances our understanding of dust-aerosol interactions with regional meteorology, aiding in better weather and climate prediction in dust-laden regions like the AP. This study explores the influence of dust aerosols on radiative fluxes over the Arabian Peninsula (AP) WRF-Chem model effectively captures the physical mechanisms of dust transport Extreme dustiness significantly modulates the radiative fluxes, thereby exerting a notable influence on the atmospheric heating rates