Evolution of the East Greenland Current from Fram Strait to Denmark Strait: Synoptic measurements from summer 2012

Abstract

We present measurements from two shipboard surveys conducted in summer 2012 that sampled the rim current system around the Nordic Seas from Fram Strait to Denmark Strait. The data reveal that, along a portion of the western boundary of the Nordic Seas, the East Greenland Current (EGC) has three distinct components. In addition to the well‐known shelfbreak branch, there is an inshore branch on the continental shelf as well as a separate branch offshore of the shelfbreak. The inner branch contributes significantly to the overall freshwater transport of the rim current system, and the outer branch transports a substantial amount of Atlantic‐origin Water equatorward. Supplementing our measurements with historical hydrographic data, we argue that the offshore branch is a direct recirculation of the western branch of the West Spitsbergen Current in Fram Strait. The total transport of the shelfbreak EGC (the only branch sampled consistently in all of the sections) decreased toward Denmark Strait. The estimated average transport of dense overflow water ( σθ > 27.8 kg/m3 and θ > 0°C) in the shelfbreak EGC was 2.8 ± 0.7 Sv, consistent with previous moored measurements. For the three sections that crossed the entire EGC system the freshwater flux, relative to a salinity of 34.8, ranged from 127 ± 13 to 81 ± 8 mSv. The hydrographic data reveal that, between Fram Strait and Denmark Strait, the core of the Atlantic‐origin Water in the shelfbreak EGC cools and freshens but changes very little in density.

Does the East Greenland Current exist in northern Fram Strait?

“…The EGC has a width of approximately 40 km and the observations show some surface intensification in its western half whereas the eastern part is more barotropic. The location and width of the shelfbreak EGC at NT1 agree well with Section 10 from Håvik et al (2017), which is located 30 km to the north of section NT1.…”

“…Velocities and current widths measured by Håvik et al (2017) were generally higher than those recorded in the present study.…”

“…3a). The 27.8 kg m ), which has a greater similarity to the EGC structure further south (Håvik et al, 2017) than the WT1 section. The offshore divergence of the isopycnals may be caused by AW intruding below, into and/or above the AAW layer at depth.…”

“…• N where a surface intensified jet, which appears to be similar to the PSW Jet of Håvik et al (2017), has a southward transport of 1.1 Sv (Fig. 3c).…”

“…• N and Denmark Strait the EGC consists of three branches: an inshore branch transporting fresh cold water, a shelfbreak branch and a branch offshore of the shelfbreak believed to be a direct recirculation of AW from the western WSC branch (Håvik et al, 2017;Nilsson et al, 2008;Woodgate et al, 1999).…”