(503g) Variations HCHO, NO2 and SO2 Vertical Column Densities from 2005 to 2017 in Five Countries Surrounding the Caspian Sea

Vertical column densities (VCD) of HCHO, NO₂, and SO₂ over the atmosphere of cities from five countries neighboring Caspian Sea including Azerbaijan, Russia, Turkmenistan, Kazakhstan and Iran during 2005-2017 years period were investigated. The most polluted coastal area of each country was chosen in this study. The VCD of gases were retrieved from the satellite data derived by Ozone Monitoring Instrument (OMI) which has been built in Aura Satellite board. This study addresses the impact of industrial, social and geopolitical development in the five Caspian littoral states on HCHO, NO₂ and SO₂ concentrations. Overall NO₂ and HCHO VCDs in all coastal countries over the Caspian Sea increased gradually by time due to the elevated oil and gas productions and their consumption, also a boost of population and rise of a number of vehicles. However, SO₂ VCD showed opposite behavior. HCHO VCD was found to be higher in Sari city located North of Iran compared to other countries due to the present of biogenic VOCs emitted from a forest land located in North of Iran.