Atmos. Chem. Phys. Discuss., 9, 19205-19241, 2009
© Author(s) 2009. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Constraint of anthropogenic NOx emissions in China from different sectors: a new methodology using multiple satellite retrievals
J.-T. Lin1, M. B. McElroy1, and K. F. Boersma2
1School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
2KNMI, Climate Observations Department, De Bilt, The Netherlands

Abstract. A new methodology is developed to constrain Chinese anthropogenic emissions of nitrogen oxides (NOx) from four major sectors (industry, power plants, mobile and residential) in July 2008. It combines tropospheric NO2 column retrievals from GOME-2 and OMI, taking advantage of their different passing time over China (9:30 a.m. local time versus 1:30 p.m.), and explicitly accounts for diurnal variations in anthropogenic emissions of NOx as well as their tropospheric lifetime and column concentrations. The approach is based on the daytime variation of NOx (when its lifetime is relatively short) alone; and potential errors in inverse modeling by neglecting horizontal transport are minimized. Separation of anthropogenic sectors relies on the estimated diurnal profiles and budget uncertainties. Our best top-down estimate suggests a national budget of 6.8 Tg N/yr (5.5 Tg N/yr for East China), close to the a priori bottom-up emission estimate from the INTEX-B mission. The top-down emissions are lower than the a priori near Beijing, in the northeastern provinces and along the east coast; yet they exceed the a priori over many inland regions. Systematic errors in satellite retrievals are estimated to lead to underestimation of top-down emissions by at most 17% (most likely 10%). Effects of other factors on the top-down estimate are typically less than 15%, including lightning, soil emissions, mixing in planetary boundary layer, anthropogenic emissions of carbon monoxide and volatile organic compounds, assumptions on emission diurnal variations, and uncertainties in the four sectors. The a posteriori emission budget is 5.7 Tg N/yr for East China.

Citation: Lin, J.-T., McElroy, M. B., and Boersma, K. F.: Constraint of anthropogenic NOx emissions in China from different sectors: a new methodology using multiple satellite retrievals, Atmos. Chem. Phys. Discuss., 9, 19205-19241, doi:10.5194/acpd-9-19205-2009, 2009.
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