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Water exchange between the continental shelf and the cavity beneath Nioghalvfjerdsbræ (79 North Glacier)
Author(s) -
Wilson N. J.,
Straneo F.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl064944
Subject(s) - geology , oceanography , continental shelf , sill , glacier , ice shelf , continental margin , bathymetry , front (military) , stratification (seeds) , water mass , geomorphology , petrology , paleontology , sea ice , cryosphere , tectonics , seed dormancy , botany , germination , dormancy , biology
The mass loss at Nioghalvfjerdsbræ is primarily due to rapid submarine melting. Ocean data obtained from beneath the Nioghalvfjerdsbræ ice tongue show that melting is driven by the presence of warm (1°C) Atlantic Intermediate Water (AIW). A sill prevents AIW from entering the cavity from Dijmphna Sund, requiring that it flow into the cavity via bathymetric channels to the south at a pinned ice front. Comparison of water properties from the cavity, Dijmphna Sund, and the continental shelf support this conclusion. Overturning circulation rates inferred from observed melt rates and cavity stratification suggest an exchange flow between the cavity and the continental shelf of 38mSv, sufficient to flush cavity waters in under 1 year. These results place upper bounds on the timescales of external variability that can be transmitted to the glacier via the ice tongue cavity.