Evaluation of spatiotemporal changes and correclations of aerosol optical depth, NDVI and climatic data over Iran

Due to the prevailing arid and semi-arid climate, Iran has always suffered from the production and spread of airborne substances, especially dust. This phenomenon is very destructive due to its direct impact on the environment and human health. Therefore, this study aimed to investigate the variation trend of aerosol optical depth (AOD), normalized difference vegetation index (NDVI), rainfall, temperature, wind speed, and correlation between AOD and climatic parameters in Iran. Data on AOD and NDVI were collected from Modis sensor images and other data from the ECMWF climate site over 2000-2019 with a spatial resolution of 10 km. The Mann-Kendall trend analysis was used to investigate the trend of changes in these parameters, and the linear correlation model was used to check the correlation between AOD and climatic data. The results of the variations trend of AOD, NDVI, and climate data showed that the trend of these parameters was different in different regions of Iran so that NDVI and rainfall had decreased by 85.13% and 67.57%, respectively, while AOD, wind speed, and the temperature had increased by 71.43%, 71.86%, and 99.37% across the country, respectively. The correlation of AOD, NDVI, rainfall, temperature and wind speed revealed that AOD had a negative correlation with NDVI and rainfall in 50.94% and 51.31% of the country, respectively, while its correlation was positive with temperature and wind speed over 68.42% and 50.36% of the country, respectively. Therefore, the increase in airborne suspended particles strongly depends on the trend of variations in vegetation cover and climatic factors, including rainfall, temperature, and wind speed, which can be well studied using satellite and climatic data with appropriate spatial and temporal resolution.