Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/os-2018-54
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
28 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Ocean Science (OS).
Does the East Greenland Current exist in northern Fram Strait?
Maren Elisabeth Richter, Wilken-Jon von Appen, and Claudia Wekerle Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
Abstract. Warm Atlantic Water (AW) flows around the Nordic Seas in a cyclonic boundary current loop. Some AW enters the Arctic Ocean where it is transformed to Arctic Atlantic Water (AAW) before exiting through Fram Strait. There the AAW is joined by recirculating AW. Here we present the first summer synoptic study targeted at resolving this confluence in Fram Strait which forms the East Greenland Current (EGC). Absolute geostrophic velocities and hydrography from observations in 2016, including four sections crossing the east Greenland shelfbreak, are compared to output from an eddy-resolving configuration of the sea–ice ocean model FESOM. Far offshore (120 km at 80.8° N) AW warmer than 2 °C is found in northern Fram Strait. The Arctic Ocean outflow there is broad and barotropic, but gets narrower and more baroclinic toward the south as recirculating AW increases the cross-shelfbreak density gradient. This barotropic to baroclinic transition appears to form the well-known EGC boundary current flowing along the shelfbreak further south where it has been previously described. In this realization, between 80.2° N and 76.5° N, the southward transport along the east Greenland shelfbreak increases from roughly 1 Sv to about 4 Sv and the warm water composition, defined as the fraction of AW of the sum of AW and AAW (AW/(AW + AAW)), changes from 19 ± 8 % to 80 ± 3 %. Consequently, in southern Fram Strait, AW can propagate into Norske Trough on the east Greenland shelf and reach the large marine terminating glaciers there. High instantaneous variability observed in both the synoptic data and the model output is attributed to eddies, the representation of which is crucial as they mediate the westward transport of AW in the recirculation and thus structure the confluence forming the EGC.
Citation: Richter, M. E., von Appen, W.-J., and Wekerle, C.: Does the East Greenland Current exist in northern Fram Strait?, Ocean Sci. Discuss., https://doi.org/10.5194/os-2018-54, in review, 2018.
Maren Elisabeth Richter et al.
Maren Elisabeth Richter et al.

Data sets

Lowered Acoustic Doppler Current Profiler (LADCP) raw data collected during POLARSTERN cruise PS100 W.-J. von Appen, T. Kanzow, and J. Schaffer https://doi.org/10.1594/PANGAEA.870995 Physical oceanog- raphy measured with CTD/Large volume Watersampler-system during POLARSTERN cruise PS100 (ARK-XXX/2) T. Kanzow, W.-J. von Appen, J. Schaffer, E. Köhn, T. Tsubouchi, N. Wilson, and A. Wisotzki https://doi.org/10.1594/PANGAEA.871025 Physical oceanography measured with ultra clean CTD/Watersampler-system during POLARSTERN cruise PS100 (ARK-XXX/2) T. Kanzow, W.-J. von Appen, J. Schaffer, E. Köhn, T. Tsubouchi, N. Wilson, P. F. Lodeiro, F. Evers, and A. Wisotzki https://doi.org/10.1594/PANGAEA.871030 Raw data of continuous VM-ADCP (vessel-mounted Acoustic Doppler Current Profiler) profile during POLARSTERN cruise PS100 (ARK-XXX/2) T. Kanzow and H. Witte https://doi.org/10.1594/PANGAEA.867798

Model code and software

Eddy-permitting and eddy-resolving simulations of the Fram Strait ocean dynamics with the Finite-Element Sea-Ice Ocean Model (FESOM) C. Wekerle, Q. Wang, W.-J. von Appen, S. Danilov, V. Schourup-Kristensen, and T. Jung https://doi.org/10.1594/PANGAEA.880569
Maren Elisabeth Richter et al.

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