@article {47481, title = {CO2 and its correlation with CO at a rural site near Beijing: Implications for combustion efficiency in China}, journal = {Atmospheric Chemistry and Physics}, volume = {10}, year = {2010}, note = {Final Manuscript in DASH}, pages = {8881-8897}, abstract = {Although China has surpassed the United States\ as the world{\textquoteright}s largest carbon dioxide emitter, in situ measurements\ of atmospheric CO2 have been sparse in China.
This paper analyzes hourly CO2 and its correlation with CO\ at Miyun, a rural site near Beijing, over a period of 51 months\ (Dec 2004 through Feb 2009). The CO2-CO correlation analysis\ evaluated separately for each hour of the day provides\ useful information with statistical significance even in the\ growing season. We found that the intercept, representing the\ initial condition imposed by global distribution of CO2 with influence of photosynthesis and respiration, exhibits diurnal\ cycles differing by season. The background CO2 (CO2,b)\ derived from Miyun observations is comparable to CO2 observed\ at a Mongolian background station to the northwest.\ \ Annual growth of overall mean CO2 at Miyun is estimated at\ 2.7 ppm yr-1 while that of CO2,b is only 1.7 ppm yr-1 similar\ to the mean growth rate at northern mid-latitude background\ stations. This suggests a relatively faster increase in the regional\ CO2 sources in China than the global average, consistent\ with bottom-up studies of CO2 emissions. For air masses\ with trajectories through the northern China boundary layer,\ mean winter CO2/CO correlation slopes (dCO2/dCO) increased\ by 2.8{\textpm}0.9 ppmv/ppmv or 11\% from 2005{\textendash}2006 to\ 2007{\textendash}2008, with CO2 increasing by 1.8 ppmv. The increase\ in dCO2/dCO indicates improvement in overall combustion\ efficiency over northern China after winter 2007, attributed\ to pollution reduction measures associated with the 2008\ Beijing Olympics. The observed CO2/CO ratio at Miyun is
25\% higher than the bottom-up CO2/CO emission ratio, suggesting\ a contribution of respired CO2 from urban residents\ as well as agricultural soils and livestock in the observations\ and uncertainty in the emission estimates.\ }, url = {http://www.atmos-chem-phys.net/10/8881/2010/acp-10-8881-2010.pdf}, author = {Wang, Yuxuan and J. William Munger and Xu, Shicheng and McElroy, Michael B. and Hao, Jiming and Nielsen, Chris P and Ma, Hong} }