Evaluation of NOx emission inventory over East Asia using satellite observations and the WRF-Chem model simulated NO2 columns

Nitrogen oxides (NOx) are emitted in large quantities by anthropogenic activity mainly from fossil fuel combustion and play a key role in the photochemically induced catalytic production of ozone. Rapid industrial and urban development in East Asia and specifically in China has resulted in unprecedented growth in NOx emissions. Remote sensing instruments have measured NO2 columns continuously during the past two decades. Spatial-temporal variations derived from these data sets provide important resources for identifying large sources and quantifying NOx emissions in this region. In addition to strong source areas, we also found the enhanced NO2 columns over Yellow Sea located between China and Korea, which imply a potentially important role of transport in local NOx budgets in this region. In order to quantify transport and emissions of NOx within East Asia, we carry out model simulations with a regional chemical transport model, the WRF-Chem model with different emission scenarios. The WRF-Chem model along with satellite measurements has been successfully used for the evaluations of bottom-up NOx emission inventories in the U.S. Finally, we evaluate and adjust the bottom-up NOx emission inventory by comparing the results of WRF-Chem simulations with the satellite NO2 columns and considering the roles of transport and emission.