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

Abstract

Abstract. The Arctic Basin exports between 600,000 and 1 million km2 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 export shows that the long-term annual mean export is about 880,000 km2, 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 km2. 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 1950–1970 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.

Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)

“…Variations in sea level pressure gradient explained approximately 60% of the variability in sea ice motion in Fram Strait (Widell et al, ), indicating the important role of atmospheric forcing on sea ice motion and distribution in Fram Strait, superimposed on a general southward drift out of the Arctic Ocean in western Fram Strait. Smedsrud et al () reported weakest export of sea ice and lowest sea ice drift speeds in Fram Strait in summer (July and August), which suggests that sea ice motion is likely even more susceptible to governing wind patterns in Fram Strait at this time of year. As seen from monthly mean winds (Figure ), wind forcing was very different in the 2 years.…”

Reassessing Sea Ice Drift and Its Relationship to Long‐Term Arctic Sea Ice Loss in Coupled Climate Models

“…Sea ice drift through Fram Strait is primarily wind driven (Kwok et al, ; Smedsrud et al, ). Trends in both Fram Strait outflow and near‐surface wind over Fram Strait have been positive since 1957 (Smedsrud et al, ). However, since 1979 there has been no significant positive trend in Arctic‐average near‐surface wind speed, and so the positive trend in Arctic‐average sea ice drift speed during this time is likely due to sea ice thinning (Rampal et al, ; Spreen et al, ).…”

“…Atmospheric winds are a key driver of sea ice motion, and numerous studies have suggested that changes in the atmospheric circulation act to accelerate the rate of sea ice loss. In particular, it has been proposed that changes in the atmospheric circulation lead to increased export of sea ice through Fram Strait (Langehaug et al, ; Rampal et al, ; Smedsrud et al, ; Wettstein & Deser, ; Williams et al, ). These changes in the atmospheric circulation are in turn connected to large‐scale changes in sea level pressure (Deser et al, ; Kwok et al, ; Rigor et al, ; Screen et al, ; Serreze et al, ; Wettstein & Deser, ).…”

Linkages between Arctic summer circulation regimes and regional sea ice anomalies

“…Figure 1a). The smaller Atlantic-side trend is due in part to the ubiquity of Fram Strait export maintaining some measure of ice cover in that sector [e.g., Smedsrud et al, 2016], although as Table 1 demonstrates, the trends in variability are small in all but the Kara Sea on the Atlantic side. Indeed, the variability in open water fraction in the Pacific sector is more than an order of magnitude greater than in than the Atlantic sector.…”