Fram Strait sea ice export variability and September Arctic sea ice extent over the last 80 years

Lars H. Smedsrud, Mari H. Halvorsen, Julienne C. Stroeve, Rong Zhang, Kjell Kloster
2016 The Cryosphere Discussions  
The Arctic Basin exports between 600,000 and 1 million km<sup>2</sup> of it's sea ice cover southwards through Fram Strait each year, or about 10 % of the sea-ice covered area inside the basin. During winter, ice export results in growth of new and relatively thin ice inside the basin, while during summer or spring, export contributes directly to open water further north that enhances the ice-albedo feedback during summer. A new updated time series from 1935 to 2014 of Fram Strait sea ice area
more » ... trait sea ice area export shows that the long-term annual mean export is about 880,000 km<sup>2</sup>, with large inter-annual and multidecadal variability, and no long-term trend over the past 80 years. Nevertheless, the last decade has witnessed increased ice export, with several years having annual ice export that exceed 1 million km<sup>2</sup>. Evaluating the trend onwards from 1979, when satellite based sea ice coverage became more readily available, reveals an increase in annual export of about +6 % per decade. The observed increase is caused by higher southward ice drift speeds due to stronger southward geostrophic winds, largely explained by increasing surface pressure over Greenland. Spring and summer area export increased more (+11 % per decade) than in autumn and winter (+2.6 % per decade). Contrary to the last decade, the 1950&ndash;1970 period had relatively low export during spring and summer, and consistently mid-September sea ice extent was higher during these decades than both before and afterwards. We thus find that export anomalies during spring have a clear influence on the following September sea ice extent in general, and that for the recent decade, the export may be partially responsible for the accelerating decline in Arctic sea ice extent.
doi:10.5194/tc-2016-79 fatcat:7wjsxuxwfjgkbb7t74j6g5w6ui