Spatiotemporal Analysis of Aerosol Over A Major Salt Lake Region: Case Study of Lake Urmia In Iran

Abstract

Lake Urmia (LU), which once had been the second largest hypersaline lake in the world, and greatest in the Middle East, has undergone severe environmental changes during recent years that have led to widespread desiccation. These changes have converted the lakebed into a significant Aeolian mineral source, which promotes aerosol plumes that can seriously impact downwind regions. A question remains as to how significant emissions are from LU as compared to others impacting the West and East Azarbaijan provinces encompassing LU. This study uses daily Aerosol Optical Depth (AOD) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) between 2001 and 2015 to show that AOD levels are significantly larger in the latter half of the study period (2008-2015) with AOD values in the West consistently being lower but approaching those of the East with time owing to a combination of increasing emissions from the West province and neighboring areas. While the interannual AOD profile over Azarbaijan resembles that of Iraq owing to transported dust, signatures of the local impact of increasing emissions is evident over the 15-year time period, especially in the months outside of the peak dust season (January, February and October) and on the immediate periphery of LU. Consequently, the spatial profile of AOD over Azarbaijan is not uniform but with distinct hot spot. The onset of the spring AOD ramp-up over Azarbaijan is shown to have started earlier (in February) when comparing 2009-2015 versus earlier years. Correlative analysis confirms that AOD is related to factors promoting dust emissions but also reveals that smoke contributes to AOD over Azarbaijan during the summer months.