Dadashi-Roudbari, A; Ahmadi, M (2020). Evaluating temporal and spatial variability and trend of aerosol optical depth (550 nm) over Iran using data from MODIS on board the Terra and Aqua satellites. ARABIAN JOURNAL OF GEOSCIENCES, 13(6), 277.

Our knowledge of the temporal-spatial variations of atmospheric aerosols is necessary because they can affect public health and air quality. This paper studied Collection 6, the product of Aerosol Optical Depth (AOD 550 nm), using the Deep Blue algorithm of moderate-resolution imaging spectroradiometer (MODIS) on board the Terra and Aqua satellites over Iran from 2003 to 2017. Long-term data of the dust using synoptic stations were also used. The results showed that the southwestern Iran, the Persian Gulf coast from Bushehr to Bandar Abbas, and the Makran coastal area in southeastern Iran have the highest seasonal means of Aerosol optical depth (AOD > 0.3) and that they are among the aerosol hotspot areas in southwestern Asia. Other regions in Iran, especially the northwest and the Zagros Mountains, have the lowest aerosol optical depth (AOD < 0.04). The highest AOD amount of Terra (0.144) and Aqua (0.156) occurs in the spring, and the lowest amount occurs in the autumn season (0.094 and 0.101 Terra and Aqua, respectively). The heights act as a barrier on the particle transport pathway and, as a result, will affect the release of dust on local and regional scales. AOD increase in Iran is more related to aerosol loading in deserts and arid areas around the country. The AOD increase during the cold period of the year in industrial cities is due to the combustion of fossil fuels and the reduction of the boundary layer height (BLH). It is because most atmospheric pollutants are released in the boundary layer and are homogenized through turbulent mixed layer processes. The most prominent active dust sources around Iran, which are the main source of aerosol increase, can be categorized into four sources: (1) Mesopotamian, (2) Northern Arabian Peninsula, (3) Elrob Elkhali desert, and (4) East Arabian Peninsula. The AOD seasonal trend showed that the most significant increasing trend occurs in autumn on the TERRA (42.82%) and Aqua (32.32%) satellites. The largest decreasing trend of AOD in Iran is observed in winter in Kermanshah province (- 0.0011 year(-1)) in western Iran and in other seasons in southeastern Iran for which meteorological changes play a major role.