Document Type : Applied Articale
Authors
1
Synoptic Meteorology expert, Kurdistan Province Meteorological Office, Sanandaj, Iran
2
Associate Professor, Sand & Dust Storm Internationa Research Center, Head of Research Institute of Meteorology and Atmospheric Sciences, Tehran, Iran
3
Assistant of Meteorological Development and Forecasting, Kurdistan Province Meteorological Office, Sanandaj, Iran
4
Assistant of Technical and network of meteorological stations, Kurdistan Province Meteorological Office, Sanandaj, Iran
5
Weather forecasting expert, Kurdistan Province Meteorological Office, Sanandaj, Iran
6
Researcher, Sand & Dust Storm international Research Center, Research Institute of Meteorology and Atmospheric Science
7
Researcher, Sand & Dust Storm International research Center, , Assistant Professor, Research Institute of Meteorology and Atmospheric Science (RIMAS)
8
Associate Professor, Sand & Dust Storm Internationa Research Center, Research Institute of Meteorology and Atmospheric Science (RIMAS)
Abstract
Dust events have been a serious environmental issue causing annual damage to infrastructure in Kurdistan Province in western of Iran. This study investigated the frequency and source regions of dust events during 1992–2022, indicating an average of approximately 32 dusty days per year. In addition, data from eight weather stations, satellite images, and aerosol optical depth (AOD) products were collected, while the HYSPLIT model was used to track the trajectories of dust particles. The results revealed that the highest dust activity occurred in spring (40%), followed by summer (27%). The intensity of dust decreases from west to east and from north to south. The examination of this event shows that dust forms and moves due to low-pressure systems over Iraq and Syria, along with unstable weather conditions. Most dust originates from sediments in riverbeds and dried wetlands in central and southern Iraq. Additional sources include deserts in Syria, Jordan, and the northern Arabian Peninsula, which produce increased dust during spring and summer.
Extended Abstract
Introduction
According to the World Meteorological Organization, dust storms are atmospheric phenomena that typically occur in arid and semi-arid regions with wind speeds exceeding 15 m/s. Dust storms usually consist of particles ranging from 0.5 to 0.1 mm and even smaller, which move in a saltation or suspended manner and can travel long distances. Due to its climatic conditions and proximity to desert regions in the east, northeast, west, and southwest, Iran frequently experiences this phenomenon. The incidence of dust storms has increased over recent decades across most parts of the country, including Kurdistan Province. Given the substantial environmental and economic impacts of dust storms, which are considered natural hazards, this study aims to examine the synoptic conditions and satellite imagery of dust events in Kurdistan Province to identify their origins and dominant patterns.
Material and Methods
The study area is Kurdistan Province, covering 28,203 km² in western Iran. This research employed statistical and synoptic analyses using data from eight synoptic meteorological stations across the province. Dust event data (coded as 06) were collected at 3-hour intervals (SYNOP reports) over a 31-year period (1992–2022). Additionally, geopotential height data at 500, 700, and 850 hPa levels, sea level pressure (SLP), and vector wind data were obtained from the National Oceanic and Atmospheric Administration (NOAA). Gridded datasets were processed and analyzed using factor analysis and hierarchical clustering (Ward’s method) to identify the prevailing synoptic patterns associated with dust generation. For a detailed case study, the large-scale dust storm occurring from July 4 to 7, 2009, was selected. In addition to synoptic analysis, Aerosol Optical Depth (AOD) was retrieved using the MOD04 L1B product from the MODIS sensor on the Terra satellite. AOD at 550 nm was analyzed using a combination of the Deep Blue and Dark Target algorithms to assess the presence of suspended dust particles. Furthermore, the HYSPLIT model was used for backward trajectory analysis at 500, 1000, and 1500 meters to trace the origin and pathway of dust-laden winds during the storm.
Results and Discussion
The analysis of dust frequency across stations revealed that Baneh (in the west) recorded the highest average of 48 dust days per year, while Kamyaran (in the south) had the lowest with 25 days. Overall, Kurdistan Province experiences an average of 32 dust days annually. Spatial distribution patterns showed that the western and central regions are more affected by dust events compared to the eastern parts, while northern regions experience more dust days than southern ones.
Three dominant synoptic patterns associated with dust events were identified based on 500 hPa geopotential height data. These patterns commonly involve low-pressure systems over Iraq and Syria, which enhance atmospheric instability over nearby deserts and position Kurdistan within the influence of deep troughs—creating favorable conditions for dust transport.
The dust storm of July 5, 2009, analyzed through AOD imagery, showed higher values in the western parts of Kurdistan and lower values in the northern and eastern parts. The AOD retrieval using Deep Blue and Dark Target algorithms effectively detected dust-affected areas. The storm’s source regions were identified as the deserts of Iraq, Syria, Jordan, Saudi Arabia, and the broader Mesopotamian plain.
Combined analysis of satellite images and HYSPLIT trajectory modeling revealed three main dust sources affecting Kurdistan:
Primary Source: Central Iraq—particularly sediment-rich riverbeds and dried ponds—as well as Jordanian deserts, most active in spring and associated with the most severe events.
Secondary Source: Northern Iraq and eastern Syria, with moderate contributions during spring and summer.
Tertiary Source: Southern Iraq and northeastern Saudi Arabia, which predominantly affect the region in the warm season but may contribute less frequently during colder months.
Conclusion
Statistical analysis confirmed that the spatiotemporal distribution of dust days across Kurdistan is shaped by both topographic features and distance from dust sources, with a west-to-east decreasing trend in frequency. Seasonally, spring and summer account for the majority of dust activity 40% and 27% respectively though events occur throughout the year at lower intensities.
Baneh station reported the highest total number of dust days (1111), while Kamyaran recorded the lowest (405) during the 31-year period. Synoptic analysis revealed three distinct atmospheric patterns contributing to dust events. AOD measurements confirmed that dust concentrations are higher in the western parts of the province. Dust tracking via satellite imagery and HYSPLIT confirmed the region’s primary external sources: central and southern Iraq, northern Saudi Arabia, and deserts in Jordan and Syria.
Acknowledgements
We sincerely thank our colleagues at the Kurdistan Meteorological Administration and the Research Institute of Meteorology and Atmospheric Sciences for their support and assistance in conducting this research.
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