Abstract
Vertical Column Density (VCD) of NO2 over the atmosphere of the Syrian Arab Republic and Yemen during the 2005-2016 period was studied to understand the potential impact of the war on the atmosphere of the two countries as well as their neighbour regions. The concentration data of NO2 was retrieved from the satellite data collected by the Ozone Monitoring Instrument (OMI) on the board of Aura Satellite and analyzed through the NCAR Command Language and Giovanni web-based application. The current study investigated the impact of energy sector, social and geopolitical situations in the two countries on NO2 concentrations before and during the war. A trend of VCDs in the aforementioned countries imply that a war has an impact on NO2 concentrations, thus a thorough analysis of the dynamics of NO2 concentrations over the atmospheres of countries experiencing war is of the essence. An analysis of the Syrian and Yemeni atmospheres before the war period showed a slightly increasing trend of NO2, which is a typical observation for oil-based countries experiencing the growth of the population, vehicles use, and the development of the industry. The war impact on the amount of NO2 in Syria can be noticed by a sharp decrease of nitrogen dioxide from 1.83×1015 molecules/cm2 till 1.15×1015 molecules/cm2 when the vigorous armed interactions have begun, however, the VCD of NO2 gradually increases in Yemen during the war from 0.56×1015 molecules/cm2 in 2015 till 0.66×1015 molecules/cm2 in 2017. The main effect of war can be explained by the considerable reduction of the population caused by refugee migration, termination of the energy sector and fossil fuel production due to disturbances in building infrastructure. Also, an important aspect of the significant number of chemical attacks and explosions during the war affect the concentration of NO2.