How Does Climate Variability Affect Dust Trend in the Middle East?

In the Middle East (ME), varying degrees of dust events occur due to its expansive arid regions. Lately, the increasing dust events in this area have become a major environmental concern. Dust particles naturally separate from the soil because of climate drivers, a regular process. However, human destructive activities as non-climate factor disrupts the environment can amplify the transport of dust on both regional and extra-regional scales. The ME comprises parts of Western Asia and Egypt, encompassing 17 countries with a combined population of around 463 million and a total area of approximately 7.9 million km2. Characterized by an arid to semi-arid climate, the region often experiences scorching summer temperatures, commonly exceeding 40oC and occasionally reaching 50oC. Precipitation is scarce in the ME, with the majority of areas receiving less than 250 mm/y. The Arabian Desert, covering an extensive area of 2.33 million km2, stands as the largest desert in the Middle East. Within its vast expanse lie distinct sub-regions, including the Rub' al Khali (Empty Quarter), Al-Dahna Desert, and An-Nafud Desert. This study has assessed the evolution of dust trends over a span of four decades (1980 to 2020) alongside alterations in climatic variables. Initially, remote sensing data for dust from the MERRA-2 dataset spanning the period between 1980 and 2020 was collected and processed. The AOD (Aerosol Optical Depth) product of MERRA-2 dataset was extracted for assessing dust concentrations. To explore the influential factors contributing to the increase in dust within the study area, three hydroclimate variables (actual evapotranspiration (AET), potential evapotranspiration (PET) and precipitation(P)) were extracted from the GLEAM (AET PET) and MSWEP (P) datasets, respectively. Subsequently, trend of dust and the climate variables were investigated by using Mann-Kendall on their associated time series, then the homogeneity tests (Pettitt test) were applied on them to detect the significant change time of each variable. This allowed for the division of the time interval for each parameter into two segments: before- and after- change time spans. This division facilitated a comparative analysis of climatic and non-climatic drivers contributing to the increase in dust, with a particular focus on the potential impact of hydroclimate variables in this context. Results reveal an upward trend in dust levels across significant regions, including Saudi Arabia, Iraq, western and southern Iran, Egypt, and Yemen (Approximately 45.86% of the study area). The observed increase is particularly prominent in areas associated with the deserts of the Rub' al Khali, Al-Dahna, and Al-Nafud, as well as countries around the Persian Gulf. Notably, surrounding the Tigris and Euphrates in Iraq, as well as the western and southwestern parts of Iran, a substantial increase in dust levels has been recorded. The findings indicate a rise in precipitation in the Tigris and Euphrates region. However, there is also an observed increase in dust. It appears that these dust events are influenced not only by climate drivers but also by non-climatic drivers. A parallel pattern is evident for AET and PET in this region.