Assimilated inversion of NOx emissions over east Asia using OMINO2 column measurements

Abstract

Assimilated inversion on a daily basis using OMI tropospheric NO2 columns is developed and applied in a regional chemical transport model (REAM) to constrain fossil fuel (FF) NOx emissions over east Asia in 2007. The iterative nature of the assimilated inversion improves upon the widely used monthly-mean inversion by accounting for the chemical feedbacks of changed NOx emissions and reducing the dependence of the a priori emissions. The assimilated a posteriori emissions from FF combustion over east Asia are 9.5 Tg N/yr comparable to 10.9 Tg N/yr of the a priori. Significant changes in the spatial distribution of FF NOx emissions are found in the assimilated inversion from the a priori or monthly-mean inversion. The assimilated inversion shows that the a priori FF NOx emission inventory tends to overestimate the emissions over the economically developed areas and underestimate over the underdeveloped areas in East China, which may reflect in part FF NOx emission reductions resulting from the urban-centric air quality controls in China. Copyright 2009 by the American Geophysical Union.