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| Titel |
Argo data assimilation into HYCOM with an EnOI method in the Atlantic Ocean |
| VerfasserIn |
D. Mignac, C. A. S. Tanajura, A. N. Santana, L. N. Lima, J. Xie |
| 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 ; 11, no. 1 ; Nr. 11, no. 1 (2015-02-11), S.195-213 |
| Datensatznummer |
250117135
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| Publikation (Nr.) |
 copernicus.org/os-11-195-2015.pdf |
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| Zusammenfassung |
| An ocean data assimilation system to assimilate Argo temperature (T) and
salinity (S) profiles into the HYbrid Coordinate Ocean Model (HYCOM) was
constructed, implemented and evaluated for the first time in the Atlantic
Ocean (78° S to 50° N and 98° W to 20° E). The system
is based on the ensemble optimal interpolation (EnOI) algorithm proposed by
Xie and Zhu (2010), especially made to deal with the hybrid nature of the HYCOM
vertical coordinate system with multiple steps. The Argo T–S profiles were
projected to the model vertical space to create pseudo-observed layer
thicknesses (Δ pobs), which correspond to the model target densities. The
first step was to assimilate Δ pobs considering the sub-state vector
composed by the model layer thickness (Δ p) and the baroclinic velocity
components. After that, T and S were assimilated separately. Finally, T was
diagnosed below the mixed layer to preserve the density of the model
isopycnal layers. Five experiments were performed from 1 January 2010 to
31 December 2012: a control run without assimilation, and four assimilation
runs considering the different vertical localizations of T, S and Δ p. The
assimilation experiments were able to significantly improve the thermohaline
structure produced by the control run. They reduced the root mean square
deviation (RMSD) of T and S calculated with respect to Argo independent data
in 34 and 44%, respectively, in comparison to the control run. In
some regions, such as the western North Atlantic, substantial corrections in
the 20 °C isotherm depth and the upper ocean heat content towards
climatological states were achieved. The runs with a vertical localization of
Δ p showed positive impacts in the correction of the thermohaline structure
and reduced the RMSD of T (S) from 0.993 °C (0.149 psu) to 0.905 °C
(0.138 psu) for the whole domain with respect to the other assimilation
runs. |
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