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| Titel |
Assessment of the representation of Antarctic Bottom Water properties in the ECCO2 reanalysis |
| VerfasserIn |
M. Azaneu, R. Kerr, M. M. Mata |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 10, no. 6 ; Nr. 10, no. 6 (2014-11-21), S.923-946 |
| Datensatznummer |
250117093
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| Publikation (Nr.) |
 copernicus.org/os-10-923-2014.pdf |
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| Zusammenfassung |
| We analyzed the ability of the Estimating the Circulation and Climate of the
Ocean – Phase II (ECCO2) reanalysis to represent the hydrographic
properties and variability of Antarctic Bottom Water (AABW) in the Southern
Ocean. We used a 20-year (1992–2011) observational database to perform
comparisons of hydrographic properties and reanalysis output for the same
time period. Four case studies based on current meter data and the AABW volume transport
estimates previously reported in the literature were also evaluated. The
opening and maintenance of an oceanic polynya in the Weddell Sea sector is
observed after 2004 in the reanalysis product. Moreover, intense deep water
production due to deep convection occurs, which leads to a scenario in which
the Weddell Sea is flooded with AABW. For this reason, our analyses focused on
the period that was identified as more reliable (1992–2004). The main
Southern Ocean oceanographic features, as well as the characteristic shape
of the regional potential temperature–salinity (θ–S) diagrams, are
coincident with observations. However, the reanalysis output produces
surface waters that are generally denser than observations due to the
reproduction of waters that are generally saltier than expected, which
probably resulted from the strong seasonality of sea ice concentrations.
Bottom waters are warmer and less dense, while intermediate waters are
statistically closest to the observations. The differences in bottom water
properties are partially due to the inability of the reanalysis to properly
reproduce the formation and export of dense waters from the shelf and the
consequent absence of the densest AABW variety for most of the analyzed
period. Despite differences in the absolute values, the upper AABW limit
(γn ≥ 28.27 kg m−3) and AABW occupied area
estimates are coincident with the observations in the World Ocean Circulation Experiment (WOCE) repeat sections
SR2 and SR4. Moreover, the AABW volume export and current velocity
variability are correlated with the observed time series in the most
important region of dense water export (i.e., the Weddell Sea). Despite the
consistency in terms of variability, the absolute volume transport and
velocity estimates are underrepresented in all cases. |
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