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| Titel |
Response of Wind-Driven Antarctic Sea-Ice Transport to External Anthropogenic Forcings |
| VerfasserIn |
F. A. Haumann, D. Notz, H. Schmidt, M. R. van den Broeke |
| 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 |
250069210
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| Zusammenfassung |
| We study mechanisms controlling the long-term changes of Southern Ocean sea-ice cover. In
particular, we focus on the response of the atmospheric circulation and the Antarctic sea ice
to stratospheric ozone depletion and greenhouse-gas increase that have been controversially
discussed. Changes of the circulation strongly influence the sea ice of the southern
hemisphere because it is rather mobile. This is related to the absence of lateral boundaries and
strong near-surface winds. Accordingly, knowledge of the affects of the external factors on
the atmospheric circulation and thus on the ice movement is crucial to understand the
evolution of the sea ice around the Antarctic continent. In terms of future changes of the
southern polar climate, Antarctic sea ice might be a key element for the amplitude of
anthropogenic warming, the stability of ice shelves, or the Southern Ocean circulation, for
example.
In order to better understand the implications of circulation changes, we particularly focus
on the role of the wind-driven sea-ice transport using model studies and satellite
observations. We use these two complementary data sources since observational records
are rather short and, hence, only allow a limited statistical analysis of long-term
trends, on the one hand. Climate models, on the other hand, are still not able to
reproduce the trends and variability of Antarctic sea ice accurately. Performing
coupled global climate model experiments, we evaluate the response of the sea ice, its
transport, and the atmospheric circulation to potential scenarios of stratospheric
ozone depletion and recovery, and greenhouse-gas increase in the period 1850 to
2100.
Our results show a strong regional relation between the trends of the northward ice transport
and the sea-ice cover which is retrieved from the satellite data. This stresses the importance
of the dynamical forcing for the Southern Ocean sea ice. Consequently, we have
analyzed the simulated wind field in order to explain the observed transport patterns.
The fully coupled model is not able to reproduce the observed sea-ice cover and
the trends accurately. However, the model simulations still allow us to identify
the impact of the external forcings on the near-surface wind field and the sea-ice
transport. Moreover, we point out problems that arise in the dynamical forcing of the
Antarctic sea ice in our model and assess possible future changes of the ice cover. |
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