Climate Change Research

Climate Change Research

A Long-term Study (2000-2014) of Aerosol Impact on Cloud Properties in Two Different Climatic Regions of Western and Southwestern Iran

Document Type : Original Article

Authors
Reza Ramezani 1
Maryam Gharaylou 2
Majid M. Farahani 2
Nafiseh Pegahfar 3
1 M.Sc. Graduate of Meteorology, Department of Space Physics, Institute of Geophysics, University of Tehran, Iran
2 Associate Professor, Department of Space Physics, Institute of Geophysics, University of Tehran, Iran
3 Assistant Professor, Atmospheric Science Research Center, Iranian National Institute for Oceanography and Atmospheric Science, Tehran, Iran
10.30488/ccr.2025.486280.1254
Abstract
Aerosols are solid or liquid particles found in the atmosphere, originating from both natural sources (including wind-blown dust, ocean evaporation, and volcanic eruptions) and human activities (like burning fossil fuels and changes in land cover). Aerosols play a significant role in the nucleation of cloud droplets and ice crystals, thereby affecting various cloud microphysical processes. Due to the complex mechanisms through which aerosols influence cloud properties, the potential effects of aerosols on thunderstorm characteristics require further investigation. In this study, the impact of aerosols on cloud properties in the western and southwestern regions of Iran during thunderstorm events from 2000 to 2014 was examined. The observational data, including cloud fraction, ice cloud optical thickness, cloud top height, and aerosol optical depth (AOD), were extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor for two different climatic regions in the west (R1) and southwest (R2) of Iran over a 15-year study period. Data from the Terra satellite (2000 to 2003) and the Aqua satellite (2003 to 2014) were utilized. Region R1, due to its geographical location and proximity to neighboring desert areas, is influenced by dust storms. Region R2, being coastal and surrounded by desert regions near the Persian Gulf, is also significantly affected by aerosols. The study results indicate that increased aerosols lead to enhanced cloud fraction in both regions (with correlation coefficients of 0.35 and 0.39, respectively). However, the effect of aerosols on ice cloud optical thickness and cloud top height varies depending on the type of aerosols. In region R1, there is a positive correlation between AOD and ice cloud optical thickness ((with a correlation coefficient of 0.54), while in R2, the correlation is negative (with a correlation coefficient of -0.25). Furthermore, there is a positive correlation between AOD and cloud top height in both regions (0.54 and 0.32, respectively) with a stronger correlation observed in region R1.
Keywords
Aerosols
AOD
cloud properties
MODIS

Subjects

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