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| Titel |
Seasonal predictability of the Arctic sea-ice in a coupled GCM: a diagnostic approach |
| VerfasserIn |
Matthieu Chevallier, David Salas y Mélia |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048014
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| Zusammenfassung |
| Sea ice is a major component of the climate system. It acts as an insulator and regulates
exchanges between the atmosphere and the ocean in the polar regions, and influences
surrounding regions, especially through freshwater transport. As it is a slow-varying medium,
sea ice may represent a source of predictability on seasonal or possibly decadal time scales in
the mid to high latitudes.
The main patterns of sea ice predictability are investigated in the CNRM-CM3.3 coupled
Global Climate model (roughly 2- horizontal resolution). A FP6/ENSEMBLES Stream 2
400-year pre-industrial simulation of CNRM-CM3.3 is studied. Such a simulation allows us
to study the intrinsic variability of climate components, in particular sea ice, in the framework
of a stabilized climate, devoid of any trend. Potential predictability of the pan-Arctic sea ice
area is investigated, using several predictors. We quantified the predictive capability of the sea
ice area itself, the sea ice volume and some areal predictors built from the subgrid ice
thickness distribution (ITD). For all months of prediction, the ice area provides a
potential delay of predictability of about 3 months. Sea ice volume predictive potential
appears weak for all months prediction, with the exception of the summer months, for
which sea ice volume is a better predictor than the sea-ice area. Using ITD-based
predictors, we highlighted two regimes of predictability. The first one, a "persistence
regime", applies to the winter (FMA) sea ice area predictability. The winter sea
ice cover can be predicted in late fall/early winter with the amount of young ice
formed from the beginning of the freeze-up in the margins. However, none of the
predictors exhibits capability better than the persistence of the sea ice area. The
second regime is a "memory regime". It applies to the summer (JJAS) sea ice area
predictability. An anomaly of sea ice area in August or September is potentially predictable
using the area covered by ice thicker than 0.9 – 1.5m up to 6 months in advance
with good confidence. These results provide an insight into the importance of the
thickness initialization for winter-spring to summer sea ice predictions, and also into
the advantage of using multi-category sea ice models in coupled climate models. |
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