First top-down diurnal adjustment to NO_x emissions inventory in Asia informed by the Geostationary Environment...

Pioneering the use of the Geostationary Environment Monitoring Spectrometer's (GEMS) observation data in air quality modeling, we adjusted Asia's NO_x emissions inventory by leveraging the instrument's unprecedented sampling frequency. GEMS tropospheric NO₂ columns served as top-down constraints, guiding our Bayesian inversion to constrain NO_x emissions in Asia during spring 2022. This enabled the model to better capture the diurnal variation in NO_x emissions, such as its morning rush hour peak, particularly when more retrievals were available each day, improving the simulation accuracy to a certain extent. The GEMS-informed adjustment reduced the extent of model underestimation of surface NO₂ concentrations from 17.38 to 5.58% in Korea and from 13.05 to 4.54% in China, showing about 9.40% and 5.77% greater improvements, respectively, compared to the adjustment based on the sun-synchronous low earth orbit observation proxy. Our findings highlight the potential of geostationary observation data in refining the diurnal cycle of inventoried NO_x emissions, thereby more effectively improving the accuracy of air quality simulations.