A continuous pathway for fresh water along the East Greenland shelf

Abstract

Export from the Arctic and meltwater from the Greenland Ice Sheet together form a southward-flowing coastal current along the East Greenland shelf. This current transports enough fresh water to substantially alter the large-scale circulation of the North Atlantic, yet the coastal current’s origin and fate are poorly known due to our lack of knowledge concerning its north-south connectivity. Here, we demonstrate how the current negotiates the complex topography of Denmark Strait using in situ data and output from an ocean circulation model. We determine that the coastal current north of the strait supplies half of the transport to the coastal current south of the strait, while the other half is sourced from offshore via the shelfbreak jet, with little input from the Greenland Ice Sheet. These results indicate that there is a continuous pathway for Arctic-sourced fresh water along the entire East Greenland shelf from Fram Strait to Cape Farewell.

Circulation Over the South‐East Greenland Shelf and Potential for Liquid Freshwater Export: A Drifter Study

“…The EGCC (Bacon, 2002; Malmberg, 1967) is a fresh (practical salinity < 34), 20 km‐wide, surface‐intensified current, with a high‐velocity core (speeds > 1 m s −1 ) carrying arctic waters and Greenland runoff equatorward (Bacon et al., 2014; le Bras et al., 2018). Recent work (Foukal et al., 2020) showed that the EGCC extends along the whole east Greenland coast, while confirming that deep troughs south of Denmark strait divert part of the EGC into the coastal current (Sutherland & Cenedese, 2009; Sutherland & Pickart, 2008). Past Cape Farewell (CF), the EGC and EGCC were first thought to merge into the West Greenland Current (WGC; Bacon, 2002), but more recent studies argue that the EGCC keeps its identity as a coastal core to become the West Greenland Coastal Current (WGCC; Lin et al., 2018).…”

Seasonal Cycle of the Coastal West Greenland Current System Between Cape Farewell and Cape Desolation From a Very High‐Resolution Numerical Model

“…In the study of Foukal et al (2020) analyzing the East Greenland boundary current system, they defined the coastal current as the inner half of the shelf and fresher than 34 salinity. Based on Foukal et al (2020)'s definition, for all the sections indicated above except OSNAP East, we define the coastal current, and thus the transports, based on integrating the model velocity fields perpendicular to each section where the salinity is lower than 34.0 and bathymetry is shallower than 250 m (see Figure 3). As for OSNAP East, we use the position of the velocity minimum offshore of the EGCC, which we define as the 40 km mark, and also where the salinity is lower than 34.0, as the offshore edge of the coastal current.…”

“…The edge of Greenland coastal current can be defined by isohaline only (34 salinity-e.g., Harden et al, 2014) or velocity only (e.g., Lin et al, 2018) or both (e.g., Sutherland et al, 2009). In the study of Foukal et al (2020) analyzing the East Greenland boundary current system, they defined the coastal current as the inner half of the shelf and fresher than 34 salinity. Based on Foukal et al (2020)'s definition, for all the sections indicated above except OSNAP East, we define the coastal current, and thus the transports, based on integrating the model velocity fields perpendicular to each section where the salinity is lower than 34.0 and bathymetry is shallower than 250 m (see Figure 3).…”

Unprecedented decline of Arctic sea ice outflow in 2018

“…Sea ice export through the Fram Strait plays a central role in the freshwater cycle connecting the Arctic and subarctic regions in the Northern Hemisphere 1 , 2 . Since the Arctic Ocean gathers 11% of the global river discharge into 3% area of the global ocean 3 , sea ice export, together with low salinity seawater carried by ocean currents, returns excess of the freshwater inputs toward lower latitudes 4 . The freshwater export mainly occurs in the Atlantic sector of the Arctic, thereby setting up surface stratification of the neighboring Nordic Seas and further downstream.…”