نوع مقاله : مقاله پژوهشی
نویسندگان
1 استادیار- گروه محیط زیست، دانشگاه آزاد اسلامی واحد اهواز
2 گروه علوم زمین، واحد علوم و تحقیقات، دانشگاه آزاد اسلامی، تهران، ایران
3 کارشناس پژوهش، پژوهشگاه هواشناسی و علوم جو، تهران، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
The dust phenomenon is one of the natural phenomenon that is formed by both human and natural factors that causes adverse environmental consequences every year in many arid regions worldwide, including Iran.
Predicting the emission and transmission of dust and aerosols can be useful to mitigate harmful effects. However, despite numerous studies, predicting dust events and their transmission remains challenging. Wind speed, vegetation, and soil structure are the most important factors in local and regional dust generation. The WRF-Chem model is a popular numerical model used for simulating wind fields, dust, and air pollution, and is of interest to researchers worldwide.
The Khuzestan province located in the southwest of Iran is affected by both cross-border and internal dust due to its geographical location. Wind plays a crucial role in the emission and transmission of dust to this region. Due to the increasing number of dust days and their intensity in the province, predicting and simulating wind and dust fields is of utmost importance. Therefore, finding the optimal configuration for the wind field during dust events and transferring it to Khuzestan is necessary. Given the significance of this issue, the aim of this study was to evaluate the wind field simulated by the WRF-Chem model under both dust and non-dust conditions, and to determine the optimal configuration for each scenario.
Data and Method
To achieve this, meteorological and environmental data from 2020 to 2022 were collected from the Iran meteorology and environmental organization. During the period of April 7-25, 2022, dust was recorded on some days in Khuzestan province, while on other days, no dust was observed. In the second step, the wind field of 700 hPa level was analyzed using GFS data in April 2022. The WRF-Chem model was run from 7 to 25 April 2022 with GFS data for four different model configurations with two boundary layer scheme YSU and MYJ as well as Lin and WMS6 cloud microphysics scheme for two horizontal resolution of 27 and 9 km.
Conclusion
The results of the model were compared with the initial GFS data and the direction and wind speed of 10 meters observed. Statistical indicators and Taylor charts were also utilized.
The results show that, the highest number of dust days in Khuzestan province occurred in Bostan and Abadan in 2022. In the three months of May, March and July the highest number of dust days in the province was obtained.
The wind filed of 700 hPa simulated by all four WRF-Chem model configurations is similar to the initial GFS data, which indicates the good model performance in simulation of wind field in the selected area, although there are differences in some details and in smaller scales.
The maximum and mean of estimated wind speed by configuration with the YSU boundary layer scheme is lower than MYJ and is closer to observational data.
During the analysis of the two bias error indices (MB) and normalized mean growth error (NMGE), the lowest values were observed at the Abadan, Mahshahr, and Omidieh stations, indicating excellent performance of the WRF-Chem model in these areas. However, weaker results were obtained at the Bostan and Ahvaz stations.
Taylor diagram shows the good model performance in estimation of 10-meters wind in Abadan, Mahshahr, Bostan, Ahvaz and Omidieh stations. The P1M6D1 and P1M2D1 have better results than P2M2D1 and P2M6D1. In this way, the Taylor diagram shows the impact of the YSU boundary layer in estimating 10-meters wind better than MYJ.
Dust distribution obtained from WRF-Chem model and the dust mass observed in the image of the MODIS sensor are in good harmony so that the dust formation center in eastern Syria and northwest of Iraq, eastern Iraq and northern Saudi Arabia is well simulated by model. In the horizontal distribution of dust, the boundary layer scheme has more effect than the microphysical scheme.
کلیدواژه‌ها [English]
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