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| Titel |
Air–sea CO2 flux in the Pacific Ocean for the period 1990-2009 |
| VerfasserIn |
M. Ishii, R. A. Feely, K. B. Rodgers, G.-H. Park, R. Wanninkhof, D. Sasano, H. Sugimoto, C. E. Cosca, S. Nakaoka, M. Telszewski, Y. Nojiri, S. E. Mikaloff Fletcher, Y. Niwa, P. K. Patra, V. Valsala, H. Nakano, I. Lima, S. C. Doney, E. T. Buitenhuis, O. Aumont, J. P. Dunne, A. Lenton, T. Takahashi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 3 ; Nr. 11, no. 3 (2014-02-06), S.709-734 |
| Datensatznummer |
250117192
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| Publikation (Nr.) |
 copernicus.org/bg-11-709-2014.pdf |
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| Zusammenfassung |
| Air–sea CO2 fluxes over the Pacific Ocean are known to be characterized
by coherent large-scale structures that reflect not only ocean subduction and
upwelling patterns, but also the combined effects of wind-driven gas exchange
and biology. On the largest scales, a large net CO2 influx into the
extratropics is associated with a robust seasonal cycle, and a large net
CO2 efflux from the tropics is associated with substantial interannual
variability. In this work, we have synthesized estimates of the net air–sea
CO2 flux from a variety of products, drawing upon a variety of approaches
in three sub-basins of the Pacific Ocean, i.e., the North Pacific
extratropics (18–66° N), the tropical Pacific
(18° S–18° N), and the South Pacific extratropics
(44.5–18° S). These approaches include those based on the
measurements of CO2 partial pressure in surface seawater
(pCO2sw), inversions of ocean-interior CO2 data, forward ocean
biogeochemistry models embedded in the ocean general circulation models
(OBGCMs), a model with assimilation of pCO2sw data, and inversions of
atmospheric CO2 measurements. Long-term means, interannual variations
and mean seasonal variations of the regionally integrated fluxes were
compared in each of the sub-basins over the last two decades, spanning the
period from 1990 through 2009. A simple average of the long-term mean fluxes
obtained with surface water pCO2 diagnostics and those obtained with
ocean-interior CO2 inversions are −0.47 ± 0.13 Pg C yr−1
in the North Pacific extratropics, +0.44 ± 0.14 Pg C yr−1 in
the tropical Pacific, and −0.37 ± 0.08 Pg C yr−1 in the South
Pacific extratropics, where positive fluxes are into the atmosphere. This
suggests that approximately half of the CO2 taken up over the North and
South Pacific extratropics is released back to the atmosphere from the
tropical Pacific. These estimates of the regional fluxes are also supported
by the estimates from OBGCMs after adding the riverine CO2 flux, i.e.,
−0.49 ± 0.02 Pg C yr−1 in the North Pacific extratropics,
+0.41 ± 0.05 Pg C yr−1 in the tropical Pacific, and
−0.39 ± 0.11 Pg C yr−1 in the South Pacific extratropics.
The estimates from the atmospheric CO2 inversions show large variations
amongst different inversion systems, but their median fluxes are consistent
with the estimates from climatological pCO2sw data and pCO2sw
diagnostics. In the South Pacific extratropics, where CO2 variations in
the surface and ocean interior are severely undersampled, the difference in
the air–sea CO2 flux estimates between the diagnostic models and ocean-interior CO2 inversions is larger (0.18 Pg C yr−1). The range of
estimates from forward OBGCMs is also large (−0.19 to
−0.72 Pg C yr−1). Regarding interannual variability of air–sea
CO2 fluxes, positive and negative anomalies are evident in the tropical
Pacific during the cold and warm events of the El Niño–Southern
Oscillation in the estimates from pCO2sw diagnostic models and from
OBGCMs. They are consistent in phase with the Southern Oscillation Index, but
the peak-to-peak amplitudes tend to be higher in OBGCMs
(0.40 ± 0.09 Pg C yr−1) than in the diagnostic models
(0.27 ± 0.07 Pg C yr−1). |
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