Effects of aerosols on lightning activity over the Arabian Peninsula

Lightning activity is one of the global natural hazards that poses significant risks on human life and numerous aspects of the society's technological infrastructure. Understanding the linkage between aerosols present in the atmosphere and lightning activity is important to further advance our knowledge of the global lightning activity cycle. The southwestern region of the Arabian Peninsula (AP) is home to one of the 500 hottest lightning spots in the world, and is not far from the largest contiguous sand desert in the world, the Empty Quarter (al-Rubea Al-Khali). Using data of individual lightning strokes from the the Global Lightning Detection Network (GLD360), in conjunction with remote sensing measurements of the aerosol optical depth (AOD) obtained at 500 nm from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra and Aqua satellites during active lightning days, we examine the evolution of lightning activity in two geographically and topologically different regions over the AP. One region extends inland to the desert (R1) and the other is in the southwest mountainous region that is close to the Red Sea (R2). In both regions, results from thunderdays-only indicate that lightning is strongly and positively correlated with the AOD loading, up to AOD ~ 0.8, after which the trend flattens or reverses direction. Results suggest the two opposite effects that aerosols could indirectly have on lightning activity are at play. Mountainous region exhibits much stronger linear relation compared to the inland region. Furthermore, both regions exhibit seasonal and asynchronous lightning activity and AOD loading. Year 2018 in R1 shows very high lightning activity, likely linked to the 2018 intense dust storms in the region.