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Multidecadal variability:

 

 

MULTIDECADAL VARIABILITY IN HIGH-LATITUDE ICE

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Ice extent anomalies (103 km2, left) and their wavelets (right) in four arctic seas provide evidence for a large amplitude multidecadal signal.
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Estimates of ice volume changes based on Neural Network (NN) assimilation technique [Belchansky et al. 2006] and Arctic Ocean freshwater content changes due to ice production. Adapted from Polyakov et al. [2007] who argued that these changes are associated with MDV.
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Kara Sea fastice thickness anomalies (cm, left) displays multidecadal variations. Wavelet analysis (right) provides further evidence of strong MDV.
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Simulated arctic ice thickness averaged over the central Arctic Ocean. Signature of multidecadal variability with thinner ice in the 1950s and recent decades and thicker ice in the 1960-70s is evident.
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History lesson is always useful. Look at the Arctic ice from the early 20th century [Encyclopedia Britannica 1904]. Shown is extreme northern ice boundary.
 
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Examination of records of fast-ice thickness and ice extent from four arctic marginal seas (Kara, Laptev, East Siberian, and Chukchi) indicates that long-term trends are small and generally statistically insignificant, while trends for shorter records are not indicative of the long-term tendencies due to strong low-frequency variability in these time series, which places a strong limitation on our ability to resolve long-term trends. Ice variability in the arctic marginal-ice zone is dominated by the MDV and, to a lesser degree, by decadal fluctuations. The MDV signal decays eastward, and is strongest in the Kara Sea, whereas in the Chukchi Sea, ice-extent and fast-ice variability is dominated by decadal fluctuations, and there is no evidence of the MDV. This is consistent with the correlation pattern of SAT station data and NAO (last figure in section "Arctic atmosphere"). Adapted from Polyakov et al. 2003b.

Our analysis of potential causes for the recent central Arctic Ocean salinification suggests that ice production and sustained draining of freshwater from the Arctic Ocean in response to winds are the key contributors. Further research is required to provide quantitative estimates of impacts freshwater export and ice production may have on high-latitude freshwater content changes. Adapted from Polyakov et al. 2007.