1Geophysical Institute, University of Bergen, Bergen, Norway
2Bjerknes Centre for Climate Research, Bergen, Norway
3University Centre in Svalbard, Longyearbyen, Svalbard
4National Snow and Ice Data Centre, University of Colorado, Boulder, USA
5Centre for Polar Observation and Modelling, University College
London, London, UK
6Geophysical Fluid Dynamics Laboratory, National Oceanic and
Atmospheric Administration, Princeton, New Jersey, USA
7Nansen Environmental and Remote Sensing Center, Bergen, Norway
Received: 01 Apr 2016 – Discussion started: 02 May 2016
Abstract. A new long-term data record of Fram Strait sea ice area export from 1935 to 2014 is developed using a combination of satellite radar images and station observations of surface pressure across Fram Strait. This data record shows that the long-term annual mean export is about 880 000 km2, representing 10 % of the sea-ice-covered area inside the basin. The time series has large interannual and multi-decadal variability but no long-term trend. However, during the last decades, the amount of ice exported has increased, with several years having annual ice exports that exceeded 1 million km2. This increase is a result of faster southward ice drift speeds due to stronger southward geostrophic winds, largely explained by increasing surface pressure over Greenland. Evaluating the trend onwards from 1979 reveals an increase in annual ice export of about +6 % per decade, with spring and summer showing larger changes in ice export (+11 % per decade) compared to autumn and winter (+2.6 % per decade). Increased ice export during winter will generally result in new ice growth and contributes to thinning inside the Arctic Basin. Increased ice export during summer or spring will, in contrast, contribute directly to open water further north and a reduced summer sea ice extent through the ice–albedo feedback. Relatively low spring and summer export from 1950 to 1970 is thus consistent with a higher mid-September sea ice extent for these years. Our results are not sensitive to long-term change in Fram Strait sea ice concentration. We find a general moderate influence between export anomalies and the following September sea ice extent, explaining 18 % of the variance between 1935 and 2014, but with higher values since 2004.
Revised: 16 Dec 2016 – Accepted: 19 Dec 2016 – Published: 13 Jan 2017
Smedsrud, L. H., Halvorsen, M. H., Stroeve, J. C., Zhang, R., and Kloster, K.: Fram Strait sea ice export variability and September Arctic sea ice extent over the last 80 years, The Cryosphere, 11, 65-79, doi:10.5194/tc-11-65-2017, 2017.