Regime shift in aerosol optical depth and long-term aerosol radiative forcing implications over the Arabian Peninsula Region

The Aerosol Optical Depth (AOD) and aerosol-induced radiative forcing trends inferred for the period 1995–2019 over the Arabian Peninsula region (APR) are extensively studied using the state-of-the-art Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalysis data. We examine the long-term AOD change for five major aerosol species: Dust (DU), Sea Salt (SS), Sulfate (SU), Black Carbon (BC), and Organic Carbon (OC) over the APR. The MERRA-2 AOD comparisons with surface measurements show that it is capable to reproduce the AOD features over APR. The total AOD over the region shows a high value in JJA with the combined effect of DU and SU being major contributors. The total AOD over APR shows an increasing trend at a rate of ∼0.05/decade. Along with an incline in DUAOD, the anthropogenic signature on total AOD also hikes contributed mainly by the SU and OC. The increase in AOD also results in a surge in aerosol-induced atmospheric forcing (ATM) with a trend of 0.13 Wm-2 year−1 and 0.15 Wm-2 year−1 during MAM and JJA respectively. Overall, the study gives a comprehensive picture of the capability of the MERRA-2 in long-term aerosol monitoring over APR, primarily situated in the “dust-belt” region.