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Titel |
Evaluation of in situ measurements of atmospheric carbon monoxide at Mount Waliguan, China |
VerfasserIn |
F. Zhang, L. X. Zhou, P. C. Novelli, D. E. J. Worthy, C. Zellweger, J. Klausen, M. Ernst, M. Steinbacher, Y. X. Cai, L. Xu, S. X. Fang, B. Yao |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 11 ; Nr. 11, no. 11 (2011-06-01), S.5195-5206 |
Datensatznummer |
250009797
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Publikation (Nr.) |
copernicus.org/acp-11-5195-2011.pdf |
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Zusammenfassung |
Quasicontinuous measurements of carbon monoxide (CO) recorded over three
years at
Mount Waliguan (WLG), a global baseline station in remote western China,
were examined using back trajectory analysis. The data include a revision to
correct the working reference scale to the WMO2000 scale and corrections for
drift in the reference gases. Between July 2004 and June 2007, CO exhibited
large fluctuations and the 5 %, 50 % and 95 %-percentiles of relevant
CO mixing ratios were 102 ppb, 126 ppb and 194 ppb. Approximately 50 % of
all observed data were selected as CO background data using a mathematical
procedure of robust local regression, with the remainder affected by
regional-scale pollution. The monthly mean background CO mixing ratios
showed a minimum in summer and a maximum in late winter, although all
seasons were affected by short-term enhancements that exceeded background
levels. The CO data were compared to values observed at the high alpine
research station at Jungfraujoch, Switzerland. Smaller seasonal amplitudes
were observed at WLG compared to the Jungfraujoch due to lower winter and
spring CO levels, however, episodic enhancements of polluted air were
greater at WLG. The air parcels arriving at WLG came predominately from the
west, except in summer when advection from the east and southeast prevailed.
Transport from the east or southeast typically brought polluted air to the
site, having passed over populated urban areas upwind. A large number of
elevated CO mixing ratios could also be associated with advection from the
northwest of WLG via the central Xinjiang Uygur Autonomous Region (XUAR) and
the Ge'ermu urban area where growing industrial activities as well as crops
residue burning provide sources of CO. Air masses passing over northwestern
Gansu were associated with relatively high CO values suggesting an
anthropogenic influence, which was likely due to anthropogenic emissions
from northwestern China (based on back-trajectory and potential source
contribution analysis and on the INTEX-B: intercontinental Chemical
Transport Experiment-Phase B). Background conditions were observed most
frequently in air parcels from remote Tibet west of WLG. The probability
that air parcels pass over regions of clean or polluted regions was further
identified using potential source contribution function (PSCF) analysis. |
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