Monthly top‐down NOx emissions for China (2005–2012): A hybrid inversion method and trend analysis

• DOI: 10.1002/2016jd025852
• Publication Date: 2017-03-22T22:55:04Z
• Authors: Zhen Qu; Daven K. Henze; Shannon L. Capps; Yi Wang; Xiaoguang Xu; Jun Wang; Martin Keller
• Keywords: Grid cell

Abstract We develop an approach combining mass balance and four‐dimensional variational (4D‐Var) methods to facilitate inversion of decadal‐scale total nitrogen oxides (NO x = NO + 2 ) emissions. In 7 year pseudo‐observation tests, hybrid posterior emissions have smaller normalized mean square error (NMSE) than that when compared true in most cases perform slightly better detecting emission magnitudes trends. Using this method, OMI satellite observations the GEOS‐Chem chemical transport model, we find more 30% increases over East China at 0.5° × 0.667° grid cell level, leading a 16% growth all from 2005 2012, whereas several urban centers decreased by 10–26% same period. From 2010 decline is found North Plain, Hubei Province, Pearl River Delta area, coinciding with China's enforcement its twelfth “Five Year Plan.” Changes individual may be different changes entire city or province, as exemplified opposite trends Beijing versus Mentougou district 2012. Also, columns do not necessarily trend due their nonlinear response influence meteorology, latter alone which can cause up interannual columns. Compared recent bottom‐up inventories, seasonality, emissions, rate national scale.