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Long‐term record of atmospheric CO 2 and stable isotopic ratios at Waliguan Observatory: Seasonally averaged 1991–2002 source/sink signals, and a comparison of 1998–2002 record to the 11 selected sites in the Northern Hemisphere
Author(s) -
Zhou Lingxi,
White James W. C.,
Conway Thomas J.,
Mukai Hitoshi,
MacClune Kenneth,
Zhang Xiaochun,
Wen Yupu,
Li Jinlong
Publication year - 2006
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2004gb002431
Subject(s) - environmental science , seasonality , northern hemisphere , southern hemisphere , atmospheric sciences , carbon cycle , sink (geography) , carbon sink , stable isotope ratio , climatology , geology , climate change , physics , geography , oceanography , ecosystem , ecology , cartography , quantum mechanics , biology , statistics , mathematics
This paper investigates seasonally averaged atmospheric CO 2 source or sink signals observed at Waliguan Baseline Observatory (WLG, 36°17′N, 100°54′E, 3816 m asl) in western China from 1991 to 2002. Both linear and geometric mean regressions as well as statistical significance test were performed between detrended CO 2 and stable isotope monthly data by means of Keeling Model and Miller‐Tans Model. The estimated slope Δδ 13 C/ΔCO 2 due to the seasonality in CO 2 and δ 13 C is (−0.050 ± 0.004)‰ ppm −1 , the mean source/sink isotopic signatures δ s (i.e., δ 13 C s and δ 18 O s ) are (−26.159 ± 1.924)‰ and (−7.662 ± 2.113)‰, respectively, and the mean atmospheric δ 13 C discrimination δ dis (i.e., δ s minus δ bg ) where the δ bg is the isotopic value of the background atmosphere was (−18.174 ± 1.959)‰ by the Keeling Model, in agreement with results from other continental background sites in the Northern Hemisphere. We suggest that exchange with terrestrial biosphere dominates the observed CO 2 , δ 13 C and δ 18 O seasonal cycles at WLG. In addition, atmospheric CO 2 and δ 13 C data from 11 selected NH sites in the NOAA ESRL air sampling network from 1998 to 2002 were analyzed and compared to the WLG data for the same period to better address common and specific features observed in this region. The annual cycle amplitude differences, secular and seasonal Δδ 13 C/ΔCO 2 discrepancies among sites will be useful to better understand carbon uptake and release especially on the Eurasian continent. The estimated δ s during certain times at each specific site could possibly provide useful information on CO 2 fluxes.