A statistical approach for identification of dust-AOD hotspots climatology and clustering of dust regimes over Southwest Asia and the Arabian Sea

Daily atmospheric composition and meteorological data from MACC and ERA-5 reanalysis, were combined to analyse the spatiotemporal variability of dust-aerosol optical depth (DAOD) and to identify the prevailing dust regimes using Empirical Orthogonal Functions (EOFs) and Principal Component Analysis (PCA), respectively, over southwest Asia and the Arabian Sea from 2003 to 2012. The analysis reveals four DAOD regimes influenced by the relative positions of the monsoon low, persistent high-pressure systems and thermal lows and the associated wind regimes. The Southeast (SE) Arabia regime, is detected over the eastern Rub-Al Khali and Oman Deserts and is associated with cyclonic flows and low-pressure systems over the southeast Arabian Peninsula, while the highest DAOD are observed over the convergence zone of Shamal and monsoon winds. The Arabian Sea regime is associated with high dust presence over the marine environment originated from arid/desert lands in Saudi Arabia, Iran and Pakistan, and the concurrent action of monsoon, Shamal and Levar winds. The Thar regime is characterized by a deep thermal low over Pakistan and strong monsoon winds acting as density currents over the desert area, resulting in highest DAOD over NW India. The Aden Gulf regime, is characterized by a ridge stretched through Sudan to Bab al-Mandab Strait and a surface high-pressure system prevailed over the eastern Mediterranean and west Arabian Peninsula, resulting in anticyclonic pathway of dust plumes from the Arabian deserts and westerly dust flows from sources in Eritrea and Sudan that accumulate dust over the Gulf of Aden.