The impact of local winds and long-range transport on the continuous carbon dioxide record at Mount Waliguan, China

Abstract

• 54 E, 3816 m asl) in western China over the period 1994-2000. The CO 2 hourly mixing ratios were segregated by horizontal wind direction/speed and vertical winds, respectively, merged by season over the entire measurement period. The short-term variability in CO 2 was examined mainly from the point of view of local winds observed at this station and isobaric back trajectory clusterconcentration analysis as for local and long-range transport influence, to permit the selection of hourly average data that is representative of background conditions. From the selected hourly data, daily, monthly and annual averages that are not influenced by local CO 2 sources and sinks be computed by discriminating the local and regional impact on the Waliguan CO 2 records. On the basis of these results, background CO 2 data were then analyzed to evaluate the averaged diurnal variation, monthly mean time series, CO 2 mixing ratio distribution in different seasons as well as averaged seasonal cycle. Annual mean and growth rate of CO 2 at Waliguan during the period of 1991 to 2000 were further discussed by supplement with NOAA/CMDL flask air sampling records at this station and other monitoring stations located at similar latitudinal band in the Northern Hemisphere. The results from this study can provide atmospheric CO 2 characteristics in Asian inland regions, and be used in other studies to improve the understanding of carbon source and sink distributions.

In situ measurement of atmospheric CO<sub>2</sub> at the four WMO/GAW stations in China

“…In 1994, the station was established as a global World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) measurement site, and was equipped to measure CO 2 mole fractions by means of a LI-COR nondispersive infrared (NDIR) analyzer. This instrument produced nearly 14 years of high-quality data, which is the longest continuous atmospheric CO 2 record in China (Zhou et al, 2003(Zhou et al, , 2005. In 2009, the aging instrument was replaced by a cavity ringdown spectroscopy (CRDS) analyzer (G1301, Picarro Inc.).…”

“…Measurements from WLG provide essential information on sources and sinks over the Eurasian continent (Zhou et al, 2004(Zhou et al, , 2005. At SDZ, LAN, and LFS, the sampling inlets were initially fixed on the top of wind poles (10 m a.g.l.).…”

Long‐term record of atmospheric CO2 and stable isotopic ratios at Waliguan Observatory: Background features and possible drivers, 1991–2002

“…The CO 2 monthly means from the in situ NDIR and GC-FID measurements are integrated (to reduce data gaps) from the selected hourly data representative of background atmospheric conditions. The system configurations and routines, CO 2 standard gases and reference scale, intercomparison experiments, calibration and quality control, impact of local winds and long-range transport on the continuous CO 2 record, background data filtering and merging methodology, etc., are described in previous studies [Zhou, 2001;Zhou et al, 2003]. …”

“…The locations of the GAW baseline stations are mostly coastal (http://www.wmo.ch/web/gcos/gif/gaw.gif) [WMO, 1993[WMO, , 2001[WMO, , 2003; World Data Center for Greenhouse Gases (WDCGG), 2003]. Funded by the United Nations and the Chinese Government, WLG was officially opened in 1994 by the China Meteorological Administration as China's first long-term research station for the continuous monitoring of greenhouse gases, ozone, aerosols, and meteorology [Wen et al, 1994;Zhou et al, 2003]. Because of its unique location the measurements from WLG provide essential information on sources and sinks from within the Eurasian continent, and they have received attention in recent years [Climate Monitoring and Diagnostic Laboratory (CMDL), 2004;Masarie and Tans, 1995;Miller et al, 2003;WMO, 2003;WDCGG, 2003] (see also http://www.cmdl.noaa.gov/ccgg/globalview).…”

Effects of Landuse Change on CH4 Soil-Atmospheric Exchange in Alpine Meadow on the Tibetan Plateau

“…The Tibetan Plateau is an average of 4,000 m above sea level with an area of about 2.57 million km 2 . As such, it is the largest grassland unit on the Eurasian continent.…”