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| Titel |
NEMO–ICB (v1.0): interactive icebergs in the NEMO ocean model globally configured at eddy-permitting resolution |
| VerfasserIn |
R. Marsh, V. O. Ivchenko, N. Skliris, S. Alderson, G. R. Bigg, G. Madec, A. T. Blaker, Y. Aksenov, B. Sinha, A. C. Coward, J. Sommer, N. Merino, V. B. Zalesny |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 5 ; Nr. 8, no. 5 (2015-05-27), S.1547-1562 |
| Datensatznummer |
250116349
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| Publikation (Nr.) |
 copernicus.org/gmd-8-1547-2015.pdf |
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| Zusammenfassung |
| An established iceberg module, ICB, is used interactively with the
Nucleus for European Modelling of the Ocean (NEMO)
ocean model in a new implementation, NEMO–ICB (v1.0). A 30-year hindcast
(1976–2005) simulation with an eddy-permitting (0.25°) global
configuration of NEMO–ICB is undertaken to evaluate the influence of
icebergs on sea ice, hydrography, mixed layer depths (MLDs), and ocean currents,
through comparison with a control simulation in which the equivalent iceberg
mass flux is applied as coastal runoff, a common forcing in ocean models. In
the Southern Hemisphere (SH), drift and melting of icebergs are in balance after
around 5 years, whereas the equilibration timescale for the Northern
Hemisphere (NH) is 15–20 years. Iceberg drift patterns, and Southern Ocean
iceberg mass, compare favourably with available observations. Freshwater
forcing due to iceberg melting is most pronounced very locally, in the
coastal zone around much of Antarctica, where it often exceeds in magnitude
and opposes the negative freshwater fluxes associated with sea ice freezing.
However, at most locations in the polar Southern Ocean, the annual-mean
freshwater flux due to icebergs, if present, is typically an order of
magnitude smaller than the contribution of sea ice melting and
precipitation. A notable exception is the southwest Atlantic sector of the
Southern Ocean, where iceberg melting reaches around 50% of net
precipitation over a large area. Including icebergs in place of coastal
runoff, sea ice concentration and thickness are notably decreased at most
locations around Antarctica, by up to ~ 20% in the eastern
Weddell Sea, with more limited increases, of up to ~ 10% in
the Bellingshausen Sea. Antarctic sea ice mass decreases by 2.9%,
overall. As a consequence of changes in net freshwater forcing and sea ice,
salinity and temperature distributions are also substantially altered.
Surface salinity increases by ~ 0.1 psu around much of
Antarctica, due to suppressed coastal runoff, with extensive freshening at
depth, extending to the greatest depths in the polar Southern Ocean where
discernible effects on both salinity and temperature reach 2500 m in the
Weddell Sea by the last pentad of the simulation. Substantial physical and
dynamical responses to icebergs, throughout the global ocean, are explained
by rapid propagation of density anomalies from high-to-low latitudes.
Complementary to the baseline model used here, three prototype modifications
to NEMO–ICB are also introduced and discussed. |
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