The emerging contribution of Tigris Euphrates basin dust emissions to extreme dust activity over the Arabian Peninsula.

The Arabian Peninsula (AP) is an epicenter of global dust activity, shaped by both local emissions and long-range transport. Recent observational studies suggest that the Tigris-Euphrates river basin (TE) is the dominant contributor to the intense dust periods over the AP. This study, for the first time, quantifies the influence of TE during these periods using a regionally tuned Weather Research and Forecasting model coupled with chemistry (WRF-Chem). Two simulations were conducted with WRF-Chem for three extreme dust seasons (March-August; 2009, 2011, and 2012): one with dust emissions from all sources, including TE, and the other with TE emissions excluded. Results show that excluding TE emissions significantly reduces mean atmospheric dust loading and decreases dust concentrations across atmospheric layers over the AP. Reduced dust concentrations enhance surface shortwave radiation, increasing solar energy potential and improving regional particulate air quality. This also contributes to cooler nighttime temperatures by limiting trapping of longwave radiation.Critically, our findings indicate that the dust transport from TE controls the intensity and frequency of dust events in the AP during the study period. Suppressing TE dust emissions leads to a substantial reduction over 50% in the occurrence of extreme dust events over the AP. At the same time, it increases the prevalence of moderate and heavy dust events across most of the region. The Kingdom of Saudi Arabia (KSA) is pursuing ambitious strategies to mitigate dust extremes. Effective action depends on identifying dominant sources and their contributions. This study quantifies the impact of the remote TE source on KSA dust extremes, offering a strong basis for targeted control measures.