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| Titel |
The importance of choosing interactive coupling on the atmosphere in the Baltic Sea region and in the North Sea-Baltic Sea transition |
| VerfasserIn |
T. Tian, F. Boberg, O. B. Christensen, J. H. Christensen |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063267
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| Zusammenfassung |
| For the purpose of a climate study around Denmark, a regional coupled atmosphere-ocean-ice
model for the North Sea (NS) and Baltic Sea (BS) is introduced with a horizontal resolution
of 6 nautical miles. The coupled model is validated in a hindcast experiment from 1990–2010
with a focus on surface quantities. Lateral boundary conditions are provided from the
ECMWF ERA-Interim reanalysis project. The impact of the interactive coupling on the
atmosphere is shown to be confined to the Baltic Sea region. Compared with the uncoupled
simulation: 1) The coupled model gives warmer winter and colder summer with a
maximum difference not exceeding 1° on an average of 21-year daily fields. 2) Winter
precipitation is slightly increased by the large-scale higher temperatures over the Baltic;
Summer precipitation (convective) is somewhat decreased and controlled by local
conditions. This seasonal difference between the two simulations varies within
10 mm month-1. The coupled regional ocean model gives results of SST and SSS with a
statistically equivalent quality to the results of the uncoupled simulation for the
NS, BS and NS-BS transition in comparison with observations. Sea ice coverage
is a sensitive quantity to a warmer winter. The integration of 21-year results of
the coupled run shows a reduction of 24% of the ice coverage in the uncoupled
one. The coupled models are free of drift and are suitable for long-term climate
simulations.
In addition to prevailing large-scale conditions, our ocean model for the NS-BS transition
with fine bathymetry (1 nm and 52 vertical layers) shows advantages in simulating local
climate. This work is the first to assess the NS-BS water transport with such a high resolution
in regional climate research and certainly in a coupled model system. It shows a great
potential to improve the prediction of climate change impacts for adaptation work in a coastal
country like Denmark. |
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