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| Titel |
Sequential assimilation of multi-mission dynamical topography into a global finite-element ocean model |
| VerfasserIn |
S. Skachko, S. Danilov, T. Janjić, J. Schröter, D. Sidorenko, R. Savcenko, W. Bosch |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023634
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| Zusammenfassung |
| Sequential assimilation of ocean dynamic topography, derived from altimeter data combined
with a referenced earth geoid, into gen- eral circulation ocean models is a complex problem.
Our previous study based on the finite-element ocean model (FEOM) revealed the existence
of a significant systematical bias between the mean dynamic topography of the model and
ocean dynamic topography. To overcome this problem an adiabatic pressure correction
method was used which reduces model drift from the mean ocean dynamic topography.
Another difficulty for the sequential assimilation of surface data is related to projection of the
surface perturbation update to the layers of the ocean model. To this end a method is used
according to which the temperature and salinity are updated following the vertical structure of
the first baroclinic mode. It is shown that the method leads to a partially successful
assimilation approach reducing the RMS difference between the model and data from 16
cm to 2 cm. This improvement of the mean state was accompanied by significant
improvement of temporal variability in our analysis. However, it remains suboptimal,
showing a tendency in the forecast phase of returning toward a free run without data
assimilation. To improve the analysis quality and to reduce the tendency of the
model to reject the changes made by the filter another approach is proposed based
on the correlation between a steric height and elevation variability. The results of
such an approach are discussed and compared to the results of our previous work. |
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