Evaluation of NOx emissions for Turkey using satellite and ground-based observations

The aim of this study was to evaluate NOx emissions from available inventories using satellite NO2 retrievals for Turkey. NOx emissions from two available inventories (EMEP and TNO) were compared with each other, differences and similarities were determined. NOx emission inventories were also compared with OMI NO2 satellite retrievals. Correlation coefficients (R2) between parameters and emissions were found in the range of 0.29–0.69 for selected high populated cities. OMI NO2 satellite retrievals overpass NO2 ground observation stations were also processed and the correlation between these observations for selected cities were found highest in summer and lowest in fall and winter. According to the comparison for individual cities, good correlations were observed for Ankara (R2 = 0.62), Izmir (R2 = 0.59) and Istanbul (R2 = 0.90). Weekly profiles and weekend/weekday ratios for ground-based and OMI NO2 observations were calculated and weekly profiles used for EMEP were also compared with observed weekly profiles. Findings showed that OMI is able to detect polluted regions in Turkey, but there are discrepancies between OMI and ground-based NO2 observations. Results also indicated issues on NOx emissions of large scale power plants in EMEP emission inventory for Turkey.