Abstract
The interannual variability of the winter sea ice area in the Barents Sea is investigated using SMMR-SSM/I data and a coupled ocean–sea ice model over the period 1979–2012. Our analysis reveals that the sea ice area in the northern and eastern parts of the Barents Sea do not covary. This contrast in behavior allows us to associate two distinct modes of variability with these two regions, with the variability of the overall Barents Sea ice cover being predominantly captured by the northern mode. Both modes show a dominant, near in-phase response to the surface wind, both being associated with different spatial patterns. The northern mode emerges in response to northwesterly wind anomalies which favor the export of ice and surface polar water from the Arctic between Svalbard and Franz Josef Land. Atlantic Water temperature anomalies, formed concomitantly with northerly wind anomalies in the vicinity of the Barents Sea Opening, also influence the northern mode in the following winter. These temperature anomalies are linked to local convergence of the oceanic heat transport. The delayed influence of the ocean on the sea ice is found primarily in the northeastern Barents Sea and occurs through the re-emergence of the Atlantic water temperature anomalies at the surface in the following fall and winter. An ocean-to-atmosphere feedback initiated by October SST anomalies in the central Barents Sea is further identified. This feedback is hypothesized to enhance the sea ice response in the northern Barents Sea by promoting the formation of meridional wind anomalies. In contrast, the eastern mode of variability of the Barents Sea ice mainly responds to wind anomalies with a strong zonal component, and is less influenced by the Atlantic Water temperature variability than the northern mode. While our results clearly highlight a role of the ocean in the Barents Sea ice variability, this role appears to be more spatially restricted following the sudden northward retreat of the ice margin in 2004. In particular, the sudden drop in the sea ice area in 2004 could not be linked to earlier Atlantic water changes in the Barents Sea Opening.
Highlights
The summer Arctic sea ice cover has exhibited significant decline over recent decades, marked by the extreme events of September 2007 and 2012 (e.g Stroeve et al, 2011; Zhang et al, 2013)
In order to analyze the variability of the winter sea ice and its relation to the atmospheric and oceanic conditions at different periods of the year, a moving average filter with a 3-month window was applied to the monthly time series of the relevant variables
For the following analysis of the sea ice variability, the sea ice concentration (SIC) deduced from the SMMR-SSM/I dataset is generally used
Summary
The summer Arctic sea ice cover has exhibited significant decline over recent decades, marked by the extreme events of September 2007 and 2012 (e.g Stroeve et al, 2011; Zhang et al, 2013). With the largest winter decrease among all the Arctic seas, the Barents Sea ice cover shows almost as strong a negative trend in winter as in the other seasons (Kern et al, 2010; Cavalieri and Parkinson, 2012) This remarkable retreat is thought to have favored cold winter conditions (Petoukhov and Semenov, 2010) or cold extremes (Gerber et al, 2014) over Europe, a link which may be enhanced in the future (Yang and Christensen, 2012). Winter sea ice concentration (SIC) anomalies in the Barents Sea have the potential to generate large scale SLP anomalies (Liptak and Strong, 2014), with possible implications for coupled atmosphere-sea ice interactions (Yang and Yuan, 2014)
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