A Satellite Data-Driven Framework to Quantify Sources and Lifetimes of Atmospheric Pollutants and the Emission Response to the COVID-19 Pandemic

Abstract:

The COVID-19 pandemic has been rapidly evolving and caused unforeseen and unprecedented disturbance to both the human societies and the Earth system. To slow down the spread of this pandemic, drastic measures have been taken worldwide, which have significantly reduced emissions in many key source regions. Remarkable drop of NO2 troposphere columns has been observed worldwide which indicates NOx emission reductions, but the quantitative connection between observed column abundance and emission is complicated by NOx chemical lifetime and atmospheric dispersion. We calibrated the atmospheric dispersion patterns in the Po Valley air basin in Italy using TROPOMI CO observations, ERA5 wind field, and EDGAR CO emission inventory. Based on the dispersion patterns, a monthly NOx lifetime climatology was retrieved from OMI NO2 product in 2004-2019 using an optimal estimation approach. This OMI-based NOx lifetime climatology was validated using TROPOMI NO2 tropospheric columns in 2018-2020. Monthly NOx emissions were then derived from OMI/TROPOMI columns, ERA5 wind, and the NOx lifetime climatology. Applications to other air basins and reactive species will also be highlighted.