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Spatial variability and decadal trend of the oceanic CO2 in the western equatorial Pacific warm/fresh water
| Title: | Spatial variability and decadal trend of the oceanic CO2 in the western equatorial Pacific warm/fresh water |
| Authors: | Ishii, Masao Browse this author | | Inoue, Hisayuki Y. Browse this author →KAKEN DB | | Midorikawa, Takashi Browse this author | | Saito, Shu Browse this author | | Tokieda, Takayuki Browse this author | | Sasano, Daisuke Browse this author | | Nakadate, Akira Browse this author | | Nemoto, Kazuhiro Browse this author | | Metzl, Nicolas Browse this author | | Wong, C. S. Browse this author | | Feely, Richard A. Browse this author |
| Keywords: | Carbon dioxide | | Partial pressure | | Dissolved inorganic carbon | | Equatorial Pacific | | Decadal trend |
| Issue Date: | Apr-2009 |
| Publisher: | Elsevier Ltd. |
| Journal Title: | Deep Sea Research Part II : Topical Studies in Oceanography |
| Volume: | 56 |
| Issue: | 8-10 |
| Start Page: | 591 |
| End Page: | 606 |
| Publisher DOI: | 10.1016/j.dsr2.2009.01.002 |
| Abstract: | Data of the partial pressure of carbon dioxide in surface seawater (pCO2sw) collected in the western equatorial Pacific (144°E - 160°W, 5°S - 5°N) since the 1980's have been used to determine the spatial variability and decadal trends in pCO2sw. A total of 109 cruises since 1983, including 30 cruises since 1990 with total dissolved inorganic carbon (TCO2) measurements, are synthesized for this zone. The western equatorial Pacific warm/fresh surface water where T ≥ 29.0 ℃ and S ≤ 34.8 is nitrate-depleted and it is moderately supersaturated with CO2 (0 < ΔpCO2 (= pCO2sw - pCO2air) / μatm < 40). A slight CO2 undersaturation (-20 < ΔpCO2 / μatm < 0) was also observed on many cruises where thin, low density layers (σt < 21.4) capped barrier layers. The undersaturation may result from net biological uptake of CO2 due to nitrogen fixation. Excluding the data in such a extremely light waters, we determined changes in the linear growth rate of pCO2sw of +0.3 ± 1.3 μatm year^[-1] for 1985 - 1990, +2.2 ± 0.7 μatm year^[-1] for 1990 - 1999, and -0.2 ± 1.0 μatm year^[-1] for 1999 - 2004. The rate of increase was +1.5 ± 0.2 μatm year^[-1] for the entire period (1985 - 2004). The variation in the rate of increase of pCO2sw is fairly consistent with the change in the rate of increase of salinity-normalized TCO2 from +2.1 ± 0.4 μmol kg^[-1] year^[-1] during 1992 - 1999 to +0.4 ± 0.9 μmol kg^[-1] year^[-1] during 1999 - 2004. These changes are anti-correlated with the decadal variation in the geostrophic mass transport from subtropics of both hemispheres into the equatorial zone in the Pacific. |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/39027 |
| Appears in Collections: | 環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 吉川 久幸
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