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Barotropic flow along depth contours is found in accordance with standard geostrophic theory. A numerical model is developed that studies the deviation from such a flow. The model gives a good approximation of the dynamical processes on the West Spitsbergen Shelf (WSS) and shows that the West Spitsbergen Current (WSC), the main gateway of Atlantic water (AW) toward the Arctic, connects more easily to the Isfjorden Trough than anywhere else along the shelf. The circulation of AW in the troughs along the WSS is here named the Spitsbergen Trough Current (STC). From hydrographical and ocean current observations it is evident that the STC is primarily barotropic and driven by the sea surface height. A connection between the along-coast wind stress and the STC is established, and it is demonstrated how the increased occurrence of winter cyclones in Fram Strait during January–February accelerates and widens the WSC. Ultimately, this results in a strengthened STC and dominance of AW on the WSS. The STC represents a slower route of AW toward the Arctic Ocean and a large heat transport toward the West Spitsbergen fjords during winter (0.2–0.4 TW toward Isfjorden). Heat flux estimates show that half of the AW heat loss in the Isfjorden Trough is due to heat loss to the surrounding water masses, while the rest is lost to the atmosphere. Sea ice production along West Spitsbergen has been reduced, or even nonexistent, in some fjords since 2006. Here, the authors argue that this is a consequence of the strong southerly wind periods along the WSS during winter.

Fjords have long been recognized for their value as sites of sediment deposition, recording past climatic conditions. Recently, Arctic fjords have been recognized as the critical gateway through which oceanic waters can impact on the stability of glaciers. Arctic fjords are also used as idealized locations to study ice-influenced physical, biological and geochemical processes. In all cases a clear understanding of the physical oceanographic environment is required to interpret and predict related impacts and linkages. In this review we consider the characteristic elements of Arctic fjords and the important dynamical processes. We show how the intense seasonality of these regions is reflected in the varying stratification of the fjords. In particular, we show that sea ice has a central role in terms of the fjord salinity which ultimately influences the exchange with oceanic waters. When the fjord is ice free, wind forcing from the intense down-fjord katabatic winds gives rise to rapidly changing cross-fjord gradients, upwelling and strong surface circulations. The stratification and dimensions of Arctic fjords mean that they are often classed as 'broad' fjords where rotational effects are important in their circulation. We refer to the link between the physical oceanographic conditions and the related depositional records throughout.

[1] Manual classification of fast ice, pack ice, and polynya (open water and thin ice) in Storfjorden from ERS-2 SAR images during winters 1998 to 2001 was used to determine model parameters in a wind-driven polynya width model. Production of ice in the classified areas was then calculated from surface heat balance. The modeled open water area occupied on average 10% of the total area and produced 58% of the total ice (T ice ). The volume of brine-enriched shelf water (BSW; V bsw ) was estimated to be in the range 0.9-1.1 Â 10 12 m 3 or 0.06-0.07 Sv (freezing period average) and 0.03-0.04 Sv (annual average). The strength of the northerly wind component seemed to dominate over net heat flux as cause of variability in T ice . Salinity of BSW (S bsw ) was found to be primarily governed by frazil ice production, whereas V bsw was mostly determined from T ice and surface salinity (initial and change during winter). Correlation studies of modeled time series of winter mean polynya area and T ice in winters 1970 to 2001 showed that interannual variability could partly be explained by variability in regional ice and ocean conditions, and partly by the strength of the southwesterlies from the North Atlantic or the North Atlantic Oscillation (NAO). Strong southerly winds (high NAO) may give less Arctic ice import and ice production in the western Barents Sea, resulting in a higher surface salinity in Storfjorden in fall. The resulting weak stability in the water column may give favorable conditions for producing large V bsw the following winter. If strong northerly winds over Storfjorden are associated with low NAO, rapid transitions from high to low NAO would give high V bsw and S bsw . The link to NAO seems to vary in time. However, the transition from weak northerly winds in winter 1999 to strong northerly winds in winter 2000 was accompanied by high observed S bsw winter 2000 in agreement with expectations.

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