Short-Term Variations of Aerosol Optical Depth during the Severe Dust Storm in 2015 over the Middle East and Long-term Variations of Aerosol Optical Properties

Abstract

Severe dust storm, with winds reaching 100 km/h, caused widespread disruption across the Middle East and northeastern part of Africa in February 2015. Residents of the regions experienced extraordinary increases in air pollution from 1 to 13 February 2015. We have analyzed changes in aerosol optical depth (AOD) during this event to identify the effect and the sources of such dust storms in the Middle East using the Moderate Resolution Imaging Spectroradiometer, the Multi-angle Imaging Spectrometer and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation. Maximum AOD values occurred on 11 of February in some dust sources including Baghdad, Damascus, Cairo, and Solar Village (Saudi Arabia), where values 0.8, 1, 1.3 and 0.7 were recorded, respectively. In Iran, maximum AOD were recorded on the 11th of February over the southwestern regions including Ahvaz and Ilam cities, reaching 1.3 and 1, respectively. The study of MISRAOD showed an increasing trend in AOD over Ahvaz and Solar Village during 2000-2015. Aerosol optical properties such as Aerosol Volume Size Distribution (AVSD) Asymmetry parameter (ASY) and Single Scattering Albedo (SSA) have been analyzed for Zanjan (AERONET site) during 2010-2013. Monthly variation of AVSD indicated that the AVSD’s peaks occur in warm months. The mean value of ASY was found to be Σ0.7 in the cloud-free atmosphere for summer that shows high pollution level in Zanjan. The Aerosol Radiative Forcing (ARF) ranged from -79 Wm-2 to -10 Wm-2 at the surface and from -25 Wm-2 to 6 wm-2 at the top of the atmosphere.