Satellite detection and model verification of NOx emissions from power plants in Northern China

We evaluate the recently increasing tropospheric NO2 columns in Northern China measured by the Ozone Monitoring Instrument (OMI) with an advanced power-plant NOx emission inventory and the NASA INTEX-B emission inventory, using a global chemical transport model (GEOS-Chem). In areas with newly built power plants the modeled and OMI-retrieved summertime average tropospheric NO2 columns increased by 55% and 47%, respectively, between 2005 and 2007. A monthly average increase of 1.79 Gg NOx emissions is calculated to lead to an increase of 1.0 x 10(15) molecules cm(-2) in the modeled NO2 columns in the study areas. Good consistency (R-2 = 0.61, slope = 1.18, n = 14) between the increased modeled and OMI-retrieved summertime average NO2 columns is found. These results suggest that NOx emissions from large power plants in Northern China can be identified and quantified using OMI retrievals with confidence. The NASA INTEX-B emission inventory appears to underestimate the NOx emissions from the industry and transportation sectors, making it more difficult to quantify power-plant emissions when they are co-located with large cities.