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Variation of atmospheric CO, δ 13 C, and δ 18 O at high northern latitude during 2004–2009: Observations and model simulations
Author(s) -
Park Keyhong,
Wang Zhihui,
Emmons Louisa K.,
Mak John E.
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd023191
Subject(s) - atmospheric sciences , environmental science , mixing ratio , northern hemisphere , δ13c , δ18o , isotopes of carbon , ozone , seasonality , chemical transport model , southern hemisphere , latitude , fossil fuel , stable isotope ratio , climatology , environmental chemistry , troposphere , chemistry , total organic carbon , geology , meteorology , ecology , geography , physics , geodesy , organic chemistry , quantum mechanics , biology
Atmospheric CO mixing ratios and stable isotope ratios (δ 13 C and δ 18 O) were measured at a high northern latitude site (Westman Islands, Iceland) from January 2004 to March 2010 in order to investigate recent multiyear trends of the sources of atmospheric carbon monoxide in the extratropical Northern Hemisphere. During this period, we observed a decrease of about 2% per year in CO mixing ratios with little significant interannual variability. The seasonal cycles for δ 13 C and δ 18 O in CO are similar to that in the CO mixing ratio, and there is a pronounced interannual variation in their seasonal extremes occurring in summer and fall, which is driven by changes in the relative contribution of different sources. Some of the sources of CO are anthropogenic in character (e.g., fossil fuel and biofuel combustion and agricultural waste burning), and some are primarily natural (e.g., oxidation atmospheric methane and other hydrocarbons and wildfires), and distinction among the various major sources can, more or less, be distinguished by the stable isotopic composition of CO. We compare our observations with simulations from a 3‐D global chemical transport model (MOZART‐4, Model for Ozone and Related Chemical Tracers, version 4). Our results indicate the observed trend of anthropogenic CO emissions is mostly responsible for the observed variation in δ 13 C and δ 18 O of CO during 2004–2009. Especially, the δ 18 O enriched sources such as fossil fuel and biofuel sources are controlling the variation. The modeling results indicate decreasing trends in the fossil fuel and biofuel source contributions at Iceland of −0.61 ± 0.26 ppbv/yr and −0.38 ± 0.10 ppbv/yr, respectively, during the observation period.