Megacity trends in OMI NO2 columns: weekday, seasonal, recession and long-term patterns

Abstract:

Ten years of OMI data are analyzed around the world to determine trends in NO2 columns in major megacities. We use a Least Squares analysis on all available OMI pixels over each individual city to separate day of week patterns, seasonal variations and annual variations. The analysis also includes the effect of wind speed, temperature, cloud cover, as well as pixel size. Bootstrapping is used to estimate the uncertainty in the results.

In this way, we identify different day of week regimes around the world, and different seasonal variations that depend on latitude as well as other factors. By accounting for these factors, we obtain more robust estimates of long term trends as well as an improved characterization of the impact of the Great Recession.