Abstract: In this study, the changes in nitrogen dioxide (NO2), carbon monoxide (CO) and sulfur dioxide (SO2) pollutant gases were examined between June 2019 and June 2021 during the COVID-19 pandemic period. For this purpose, monthly and annual averages of Sentinel-5P TROPOspheric Monitoring Instrument (TROPOMI) values were calculated on the Google Earth Engine (GEE) platform. According to the results obtained using the GEE platform, the average column density values of NO2, CO, and SO2 in the Marmara Region between the selected dates were calculated as 8.40E-05 mol/m2, 3.23E-02 mol/m2, and 3.75E-04 mol/m2, respectively. During the lockdown, these values decreased to 7.84E-05 mol/m2, 3.05E-02 mol/m2 and 2.75E-04 mol/m2 respectively. According to TROPOMI data, these three gas column density values showed a decreasing trend during the COVID-19 pandemic lockdown period. However, in a 25-month examination in general, these three gas values showed an increasing trend due to population growth, industrialization, and increasing traffic density.
Keywords: Sentinel-5P, TROPOMI, NO2, CO, SO2, Google Earth Engine, COVID-19