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| Titel |
Estimating temporal and spatial variation of ocean surface pCO2 in the North Pacific using a self-organizing map neural network technique |
| VerfasserIn |
S. Nakaoka, M. Telszewski, Y. Nojiri, S. Yasunaka, C. Miyazaki, H. Mukai, N. Usui |
| 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 ; 10, no. 9 ; Nr. 10, no. 9 (2013-09-26), S.6093-6106 |
| Datensatznummer |
250085338
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| Publikation (Nr.) |
 copernicus.org/bg-10-6093-2013.pdf |
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| Zusammenfassung |
| This study uses a neural network technique to produce maps of the partial
pressure of oceanic carbon dioxide (pCO2sea) in the North
Pacific on a 0.25° latitude × 0.25° longitude grid
from 2002 to 2008. The pCO2sea distribution was computed using
a self-organizing map (SOM) originally utilized to map the
pCO2sea in the North Atlantic. Four proxy parameters – sea
surface temperature (SST), mixed layer depth, chlorophyll a concentration,
and sea surface salinity (SSS) – are used during the training phase to enable
the network to resolve the nonlinear relationships between the
pCO2sea distribution and biogeochemistry of the basin. The
observed pCO2sea data were obtained from an extensive dataset
generated by the volunteer observation ship program operated by the National
Institute for Environmental Studies (NIES). The reconstructed
pCO2sea values agreed well with the pCO2sea
measurements, with the root-mean-square error ranging from 17.6 μatm
(for the NIES dataset used in the SOM) to 20.2 μatm (for
independent dataset). We confirmed that the pCO2sea estimates
could be improved by including SSS as one of the training parameters and by
taking into account secular increases of pCO2sea that have
tracked increases in atmospheric CO2. Estimated pCO2sea
values accurately reproduced pCO2sea data at several time
series locations in the North Pacific. The distributions of
pCO2sea revealed by 7 yr averaged monthly
pCO2sea maps were similar to Lamont-Doherty Earth Observatory
pCO2sea climatology, allowing, however, for a more detailed
analysis of biogeochemical conditions. The distributions of
pCO2sea anomalies over the North Pacific during the winter
clearly showed regional contrasts between El Niño and La Niña years
related to changes of SST and vertical mixing. |
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