Study of the back trajectory density of extreme dust events in the eastern Mediterranean Sea

Abstract Extreme events of dust storms have received great attention recently due to the increase in the number of occurrences of storms in recent years, as they have a major impact on all aspects of life, including human health and their impact on the ecosystem, agriculture, industry and other aspects related to life. The aim of this study is to verify the increasing of extreme dust storms in the study area (Iraq), and also to study the spatial distribution of the back trajectory density of external sources of air masses for 4 days and 10 days during the study period, using a LaGrange approach over Iraq. The aerosol index data that was used was taken from the Ozone Monitoring Instrument; the dataset includes daily level-3 information with a spatial resolution of 1° × 1° grid covers Iraq. In extreme events are defined as those events whose total occurrence of extreme dust events is higher than the 0.99 percentile for the period from 2014 to 2023. To further investigate the Hybrid Single-Particle LaGrange Integrated trajectory (HYSPLIT), this model was used to study the dynamic mechanism that led to the production of extreme dust storm events and its relationship to general circulation. The back trajectory density of the air masses affecting on the study area was studied at levels 100, 500, and 1500 m. The origin of the air mass is distributed of 3 types of air mass from the North to South of the study area and recirculation in the Middle of the study area. Most of the dust storms are caused by air masses from outside the study area, considering the desert geographic region surrounding Iraq. The total number of extreme cases of dust storms during the study period from 2014 to 2023 was 385 extreme events. The highest number of extreme events of dust storms during the study period for all stations was in the years (2015, 2016, 2017, 2018), and the highest was in 2016 with 74 cases. The years with the lowest extreme events were (2014, 2019, 2020, 2021, 2022, 2023). The lowest year with the number of cases was 2014, and 2023 with 5 cases each year. There is no correlation between the number of extreme dust storms and the climate index Nao, Ao, EA. The results obtained in this study provide a better understanding of the nature and behavior of extreme dust storms in the study area (Iraq) on a large scale.