@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 = {<a data-url="https://dash.harvard.edu/handle/1/28349407" href="https://dash.harvard.edu/handle/1/28349407" target="_blank" title="">Final Manuscript in DASH</a>},
	pages = {8881-8897},
	abstract = {Although China has surpassed the United States\&nbsp;as the world{\textquoteright}s largest carbon dioxide emitter, in situ measurements\&nbsp;of atmospheric CO2 have been sparse in China.\&nbsp;This paper analyzes hourly CO2 and its correlation with CO\&nbsp;at Miyun, a rural site near Beijing, over a period of 51 months\&nbsp;(Dec 2004 through Feb 2009). The CO2-CO correlation analysis\&nbsp;evaluated separately for each hour of the day provides\&nbsp;useful information with statistical significance even in the\&nbsp;growing season. We found that the intercept, representing the\&nbsp;initial condition imposed by global distribution of CO2 with\&nbsp;influence of photosynthesis and respiration, exhibits diurnal\&nbsp;cycles differing by season. The background CO2 (CO2,b)\&nbsp;derived from Miyun observations is comparable to CO2 observed\&nbsp;at a Mongolian background station to the northwest.\&nbsp;Annual growth of overall mean CO2 at Miyun is estimated at\&nbsp;2.7 ppm yr-1 while that of CO2,b is only 1.7 ppm yr-1 similar\&nbsp;to the mean growth rate at northern mid-latitude background\&nbsp;stations. This suggests a relatively faster increase in the regional\&nbsp;CO2 sources in China than the global average, consistent\&nbsp;with bottom-up studies of CO2 emissions. For air masses\&nbsp;with trajectories through the northern China boundary layer,\&nbsp;mean winter CO2/CO correlation slopes (dCO2/dCO) increased\&nbsp;by 2.8{\textpm}0.9 ppmv/ppmv or 11\% from 2005{\textendash}2006 to\&nbsp;2007{\textendash}2008, with CO2 increasing by 1.8 ppmv. The increase\&nbsp;in dCO2/dCO indicates improvement in overall combustion\&nbsp;efficiency over northern China after winter 2007, attributed\&nbsp;to pollution reduction measures associated with the 2008\&nbsp;Beijing Olympics. The observed CO2/CO ratio at Miyun is\&nbsp;25\% higher than the bottom-up CO2/CO emission ratio, suggesting\&nbsp;a contribution of respired CO2 from urban residents\&nbsp;as well as agricultural soils and livestock in the observations\&nbsp;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}
}
