Assessing the distribution and growth rates of NOx emission sources by inverting a 10-year record of NO2 satellite columns

Tropospheric NO2 columns retrieved from the GOME and SCIAMACHY satellite instruments between January 1997 and December 2006 are used together with the IMAGES CTM and its adjoint to construct a top-down inventory for NOx emissions, with a focus on anthropogenic sources. The influence of the emission updates on the chemical lifetime of NOx is taken into account, and found to have a significant impact on the results. Anthropogenic emission trends are inferred over industrialized regions of the Northern Hemisphere. The largest emission increases are found over eastern China, and in particular in the Beijing area (growth rate of 9.6%/yr), whereas important emission decreases are calculated over the United States (−4.3%/yr in the Ohio River Valley), and to a lesser extent over Europe (−1.4%/yr in Germany, −1.0%/yr in the Po Basin). The emission changes result in significant trends in surface ozone, amounting to more than 15%/decade over large parts of China in summertime.