Sources and distribution of fresh water around Cape Farewell in 2014

Type Article
Date 2019-12
Language English
Author(s) Benetti M.1, Reverdin G.1, Clarke J.S.2, 3, Tynan E.2, Holliday N.P.4, Torres‐valdes S.4, Lherminier PascaleORCID5, Yashayaev I.6
Affiliation(s) 1 : Sorbonne Université, CNRS/IRD/MNHN (LOCEAN) Paris, France
2 : Ocean and Earth Sciences, University of Southampton, Waterfront Campus, National Oceanography Centre Southampton Southampton ,United Kingdom
3 : Chemical Oceanography, GEOMAR Helmholtz‐Zentrum für Ozeanforschung Kiel ,Germany
4 : National Oceanography Centre, Europena Way Southampton ,UK
5 : Ifremer, Univ. Brest, CNRS, IRD, Laboratoire d'Océanographie Physique et Spatiale (LOPS), IUEM Plouzané ,France
6 : Department of Fisheries and Oceans, Ocean Sciences DivisionBedford Institute of Oceanography Dartmouth N.S. ,Canada
Source Journal Of Geophysical Research-oceans (2169-9275) (American Geophysical Union (AGU)), 2019-12 , Vol. 124 , N. 12 , P. 9404-9416
DOI 10.1029/2019JC015080
WOS© Times Cited 3
Keyword(s) fresh water, water isotopes, south Greenland currents
Abstract

We investigate the origin of freshwater on the shelves near Cape Farewell (south Greenland) using sections of three hydrographic cruises in May (HUD2014007) and June 2014 (JR302 and Geovide) 2014. We partition the freshwater between meteoric water sources and sea ice melt or brine formation using the δ18O of sea water. The sections illustrate the presence of the East Greenland Coastal Current (EGCC) close to shore east of Cape Farewell. West of Cape Farewell, it partially joins the shelf break, with a weaker near‐surface remnant of the EGCC observed on the shelf southwest and west of Cape Farewell. The EGCC traps the freshest waters close to Greenland, and carries a brine signature below 50m depth. The cruises illustrate a strong increase in meteoric water of the shelf upper layer (by more than a factor 2) between early May and late June, likely to result from East and South Greenland spring melt. There was also a contribution of sea ice melt near the surface but with large variability both spatially and also between the two June cruises. Furthermore, gradients in the freshwater distribution and its contributions are larger east of Cape Farewell than west of Cape Farewell, which is related to the East Greenland Coastal Current being more intense and closer to the coast east of Cape Farewell than west of it. Large temporal variability in the currents is found between different sections to the east and south‐east of Cape Farewell, likely related to changes in wind conditions.

Plain language summary

Three successive hydrographic cruises in the spring 2014 surveyed the water masses on the shelf near Cape Farewell in South Greenland. Using information from the isotopic composition of sea water as well as salinity, it is possible to partition contributions of fresh water input on the shelves (compared to the nearby open ocean) that result either from inputs from river, glacier or precipitation, or from the melt (or formation) of sea ice. This is related to the ocean currents that were observed or deduced from hydrography. These indicate fresh water trapped near the coast associated with the East Greenland Coastal Current, mostly on the south‐east side, but also partially found at the surface on the western side. At subsurface, this current carried water enriched in brines (due to upstream sea ice formation). A large variability is observed over the 45 days spanned by the spring cruises both for the fresh water content and sources, than for the current structure.

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How to cite 

Benetti M., Reverdin G., Clarke J.S., Tynan E., Holliday N.P., Torres‐valdes S., Lherminier Pascale, Yashayaev I. (2019). Sources and distribution of fresh water around Cape Farewell in 2014. Journal Of Geophysical Research-oceans, 124(12), 9404-9416. Publisher's official version : https://doi.org/10.1029/2019JC015080 , Open Access version : https://archimer.ifremer.fr/doc/00591/70349/