Abstract
AbstractThe West Spitsbergen Current, which flows northward along the western Svalbard continental slope, transports warm and saline Atlantic water (AW) into the Arctic Ocean. A combined analysis of high‐resolution seismic images and hydrographic sections across this current has uncovered the oceanographic processes involved in horizontal and vertical mixing of AW. At the shelf break, where a strong horizontal temperature gradient exists east of the warmest AW, isopycnal interleaving of warm AW and surrounding colder waters is observed. Strong seismic reflections characterize these interleaving features, with a negative polarity reflection arising from an interface of warm water overlying colder water. A seismic‐derived sound speed image reveals the extent and lateral continuity of such interleaving layers. There is evidence of obliquely aligned internal waves emanating from the slope at 450–500 m. They follow the predicted trajectory of internal S2 tidal waves and can promote vertical mixing between Atlantic and Arctic‐origin waters.
Highlights
Fram Strait, a 450 km wide passage located between Greenland and Svalbard, is a critical exchange point for the ocean circulation of the North Atlantic [Hunkins, 1990]
The resultant Arctic water is exported back through Fram Strait, where it contributes significantly to the heat and freshwater budgets of the North Atlantic (Figure 1a) [Schauer et al, 2004]. This water mass can impact the southward-flowing limb of the North Atlantic meridional overturning circulation through its effects on ocean density, which controls the efficiency of deep convection in the Nordic Seas [Rabe et al, 2013]
A h-S plot (Figure 1c) of the CTD data along transect AD shows that water masses of four categories are present: Polar Water (PW) (h > 08C; S < 34.9), two types of Atlantic water (AW) (h > 28C, S > 34.91; 08C < h < 28C, S > 34.91), and Arctic Intermediate Water (AIW, 21.18C < h < 08C; 34.7 < S < 34.9)
Summary
Fram Strait, a 450 km wide passage located between Greenland and Svalbard, is a critical exchange point for the ocean circulation of the North Atlantic [Hunkins, 1990]. The resultant Arctic water is exported back through Fram Strait, where it contributes significantly to the heat and freshwater budgets of the North Atlantic (Figure 1a) [Schauer et al, 2004] This water mass can impact the southward-flowing limb of the North Atlantic meridional overturning circulation through its effects on ocean density, which controls the efficiency of deep convection in the Nordic Seas [Rabe et al, 2013]. Internal waves, and the interaction with local water masses remain sparsely investigated due to the scarce observational records both within Fram Strait and on the West Spitsbergen shelf and upper slope Owing to their coarse lateral resolution (typically >10 km), conventional conductivity-temperaturedepth (CTD) sections have considerable uncertainty in resolving the horizontal oceanic thermohaline structures associated with mixing processes. We interpolated the time series of eastward (u) and northward (v) flowing current components onto an hourly time base as an input requirement for T_TIDE
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