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Oceanic Suess effect of δ 13 C in subpolar region: The North Pacific
Author(s) -
Tanaka Takayuki,
Watanabe Yutaka W.,
Watanabe Shuichi,
Noriki Shinichiro,
Tsurushima Nobuo,
Nojiri Yukihiro
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018503
Subject(s) - dissolved organic carbon , oceanography , water mass , deep water , geology , amplitude , environmental science , subtropics , carbonate , carbon cycle , atmospheric sciences , climatology , chemistry , ecosystem , physics , ecology , biology , quantum mechanics , organic chemistry
We propose a simple approach for estimating the recent oceanic Suess effect of δ 13 C in the subpolar region of the North Pacific, an area which experiences a large seasonal variability of carbonate species, due to the biological activity and vertical water mixing. This approach is based simply on time‐series data of δ 13 C from July 1997 to July 2001 and an equation of the Fourier sine expansion. Applying our approach to the fixed sampling location in the western North Pacific, station ‘KNOT’, we estimated values of −0.012‰‐δ 13 C yr −1 for the Suess effect of δ 13 C with an amplitude of 1.3‰‐δ 13 C and 1.0 μmol‐C kg −1 yr −1 for the increase rate of dissolved inorganic carbon with an amplitude of 134 μmol‐C kg −1 in surface water. The Suess effect of δ 13 C in this region was a similar value to that estimated in the Southern Ocean producing the deep water, while it was half as much as values estimated in the subtropical regions which experience a small seasonal variability. The ratio of Suess effect to the increase rate of dissolved inorganic carbon was −0.012‰ (μmol kg −1 ) −1 , which was different from the global mean values calculated by recent modeling study. Therefore, we conclude that the Suess effect of δ 13 C in the polar and subpolar regions is generally smaller than found in other regions, suggesting that it is necessary to reevaluate the uptake rate of anthropogenic carbon which has been based on the assumption that the ratio is uniform over the entire ocean.