Sources and Distribution of Fresh Water Around Cape Farewell in 2014. Issue 12 (20th December 2019)

• Record Type: Journal Article
• Authors: Benetti, M.; Reverdin, G.; Clarke, J. S.; Tynan, E.; Holliday, N. P.; Torres‐Valdes, S.; Lherminier, P.; Yashayaev, I.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 12(2019)
• Page Start: 9404
• Page End: 9416
• Publication Date: 2019-12-20
• Subjects: fresh water -- water isotopes -- south Greenland currents; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2019JC015080
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: We investigate the origin of fresh water on the shelves near Cape Farewell (south Greenland) using sections of three hydrographic cruises in May (HUD2014007) and June 2014 (JR302 and Geovide). We partition the fresh water between meteoric water sources and sea ice melt or brine formation using the δ 18 O 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 50‐m 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 EGCC 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 southeast 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 freshwater 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 not only with the East Greenland Coastal Current, mostly on the southeast 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 freshwater content and sources, than for the current structure. Key Points: Surveys in spring 2014 show a large variability in fresh water and its composition with often a small signal of brine formation at subsurface in the East Greenland Coastal Current (EGCC) The EGCC is found close to the coast east of Cape Farewell, whereas it is found closer to the shelf Break, west of Cape Farewell