Keywords:Inversion, Emission inventory, Chemical transport model, Satellite observation, NOx emission
We developed a quick update system for an emission inventory with an inversion technique, and extended NOx emission in Regional Emission inventory in the ASia version 2.1 (REAS 2.1) through 2009–May 2013 with satellite-observed tropospheric NO2 vertical column densities (VCDs) and a chemical transport model. The observed NO2 VCDs over the eastern Chinese region exhibited a drastic inter-annual variation over the eastern Chinese region due to the socioeconomic condition. During 2008–2009, the growing of the NO2 VCD became sluggish because of pollutant controls by the 2008 Beijing Olympic game and the global depression, but revived in 2010 with a growth rate of 37.3%/year. The modeled NO2 VCD with the updated emission successfully followed the inter-annual variation, and reproduced the observed seasonal cycle in which summer and winter have the seasonal bottom and peak, respectively. We estimated the updated Chinese anthropogenic NOx emissions during 2009–2012 to be 25.7, 27.3, 28.2, 28.4 Tg/year; they fell within the range of the various estimates in the literatures. An annual growth rate during 2009–2012 and 2005–2012 was estimated to be 3.5%/year (0.9 Tg/year) and 5.3%/year (1.1 Tg/year), respectively. The system has the capability of updating NOx emission in near real-time (NRT) for air qualtiy forecasting. Figure shows annual anthropogenic NOx emission from China. Numbers in the panels represent annual Chinese anthropogenic NOx emission. Other estimates of Chinese NOx emission are also shown by symbols.