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| Titel |
Influence of the Gulf Stream on the Barents Sea ice retreat and Eurasian coldness |
| VerfasserIn |
Kazutoshi Sato, Jun Inoue, Masahiro Watanabe |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250095010
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| Publikation (Nr.) |
 EGU/EGU2014-10449.pdf |
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| Zusammenfassung |
| Abnormal winter sea-ice retreat over the Barents Sea has been considered as a leading clue to
the recent midlatitude severe winters. Barents Sea is considered as a hot spot for the rapid
Arctic climate change due to the intense air-sea interaction induced by the sea-ice decrease;
however, the underlying mechanisms remain uncertain, in particular causal relation of sea-ice
retreat and atmospheric forcing and response. To understand this causality, we selected
typical cases, defined as averaged warm and averaged cold years of December using the
NCEP Climate Forecast System Reanalysis (CFSR). The composite analysis, revealed
that anticyclonic anomaly is obvious over the northwestern Eurasia. The western
Barents Sea and Sbarvard locates at the strong pressure gradient zone, prevailing
southerly winds. Over the Barents Sea, the difference in daily mean air temperature
between warm and cold winters is more than 10°, suggesting that warm advection
prevails during warm years. Therefore, during warm years, decrease in sea-ice cover
is induced by southerly warm advection. The positive anomalies of precipitation
from the southeast of Greenland to Barents Sea and negative anomalies of them
from Nordic Sea to western Eurasia means the poleward shift of cyclone tracks,
suggesting that the moisture transport is also changed poleward. Because the cyclones
tend to shift poleward in less sea ice year over the Barents Sea, it is natural that the
snow depth over the sea ice near the Fram Strait shows a positive anomaly during
warm winters. Here we show that the poleward shift of sea surface temperature over
the Gulf Stream, where is situated upstream from the Barents Sea, modifies the
horizontal distribution of tropospheric condensational heating resulted from change
in convection over the warm current, likely acting as a bridge to the Barents Sea
by forcing planetary waves. This remote atmospheric response modifies cyclone
tracks poleward, resulting in anomalous warm advection over the Barents Sea sector. |
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