Aerosol Optical Depth variability over the Arabian Peninsula as inferred from satellite measurements

Aerosol abundance from widespread deserts over the Arabian Peninsula (AP) plays an important role in the regional climate and air quality. This study investigates the spatio-temporal variability of Aerosol Optical Depth (AOD) ranging from seasonal to inter-annual time scales during the period 2003-2016 using satellite retrievals from MISR and MODIS, together with ground-based observations from the Aerosol Robotic Network (AERONET) available during the period 2003-2012 over the AP. The MODIS AOD (MISR AOD) observations exhibit 0.81 and 0.85 (0.71 and 0.76) correlations with ground-based observations during the wet and dry seasons, respectively. The correlations were also found to be significant with respect to the surface monitoring station at Solar village in Saudi Arabia. Our observational analysis reveals higher (lower) concentrations of AOD during dry (wet) seasons over the AP. The observed AODs indicate similar spatial distributions over annual and seasonal time scales, with high AODs over the Southern Red sea (SR), and the Northeast AP, and lower AODs over the central and southern end of the AP. It is also observed that the AOD exhibits year-to-year variations over different sub-regions of the AP. Analyses of the inter-annual variability over the AP reveals a significant relationship between the AOD and El Niño-Southern Oscillation (ENSO) during the summertime. Furthermore, positive AOD anomalies over the AP can be closely linked with the intensification of the westerly jet at the Tokar Gap during La Niña phases. Enhanced monsoon associated heat low over the AP during La Niña phases further favors greater uplift and saltation of dust from desert regions.