Document Type : Original Article
Authors
1
PhD student of Climatology, Zanjan University, Iran
2
Associate Professor, Faculty member of Zanjan University, Iran
3
Assistant Professor, Faculty member of Zanjan University, Iran
Abstract
Airborne particles have a significant effect on the characteristics of precipitation and directly affect the climate of the region and human life. Aerosols, which play an essential role in cloud formation and radiation balance regulation, can affect the intensity, frequency, geographical distribution, extent, and timing of precipitation. However, due to variations in aerosol properties, different types of precipitation, vertical distribution of aerosols, and meteorological conditions, discrepancies are observed among the results of current studies. Scientific advances in recent research have produced significant developments, but understanding the effects of aerosols on precipitation remains challenging and complex. In this research, the AOD index and geographically weighted regression model have been used to investigate the relationship and possible impact of aerosols on precipitation in Iran. For this purpose, the daily data of the Modis Mod08 product and the daily rainfall data during the statistical period of 2000-2022 were used. Also, to reveal the type of aerosols affecting precipitation, daily data of the MERRA-2 model and multivariate regression method model were used. The results showed that considering all three cases, i.e. the relationship between AOD index values with precipitation on the same rainy day, AOD index values one day before precipitation with precipitation the next day, and AOD index values two days before precipitation with precipitation on the given day. Opinion, there is a correlation between these two variables in all three situations at a minimum of 0.3 to a maximum of 55.7. The results of analyzing the spatial distribution of significant pixels showed that this distribution has a special pattern in such a way that most of these pixels are located in the three regions of the southeast (Kerman, Sistan and Baluchistan, and Hormozgan provinces), the western region (Kurdistan province, Hamadan and Lorestan) and the northeast region (Khorasan, Semnan and the eastern part of Mazandaran) are concentrated. In the investigation of the types of aerosols effective in precipitation, it was found that the most effective types of aerosols in precipitation in these areas were dust particles with diameters of PM10 and PM2.5. Also, comparing the amount of precipitation with the AOD index on a rainy day shows that on the days when the index value is high (values close to 1 and more), the amount of precipitation that occurred in one day has increased significantly. In other words, with the increase in the density of aerosols, more intense rains have occurred.
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