CO2 and its correlation with CO at a rural site near Beijing: Implications for combustion efficiency in China


Yuxuan Wang, J. William Munger, Shicheng Xu, Michael B. McElroy, Jiming Hao, Chris P Nielsen, and Hong Ma. 2010. “CO2 and its correlation with CO at a rural site near Beijing: Implications for combustion efficiency in China.” Atmospheric Chemistry and Physics, 10, Pp. 8881-8897. Publisher's Version


Although China has surpassed the United States
as the world’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±0.9 ppmv/ppmv or 11% from 2005–2006 to
2007–2008, 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.


Final Manuscript through DASH
DOI: 10.5194/acp-10-8881-2010
Last updated on 07/31/2019