ORCID Profile
0000-0003-1974-319X
Current Organisation
Carleton University
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Publisher: American Geophysical Union (AGU)
Date: 30-08-2021
DOI: 10.1029/2021JC017324
Abstract: Milne Ice Shelf is located at the mouth of Milne Fiord (82.6°N, 81.0°W), on Ellesmere Island, Nunavut. This floating ice feature is attached to both sides of the fjord. During the melt season, the ice shelf acts as a floating barrier preventing surface runoff in Milne Fiord from flowing freely to the ocean. This results in a permanent layer of freshwater that floats on top of the seawater of the fjord, commonly known as an epishelf lake. Few studies address the physical characteristics of epishelf lakes. Here, winter data from a mooring installed in Milne Fiord epishelf lake during 2011–2019 is analyzed in the framework of a one‐dimensional model in order to study mixing in the upper water column and infer the characteristics of a basal channel in the ice shelf. The results show that vertical mixing rates are higher in the epishelf lake than in the seawater below. Estimation of the Richardson number using a geostrophic balance approach reveals that enhanced mixing in the epishelf lake is associated with horizontal temperature gradients. In contrast to most studies on basal channels in Greenland and Antarctica, the results presented here show the basal channel of Milne Ice Shelf is apparently not evolving (melting) rapidly.
Publisher: Copernicus GmbH
Date: 12-09-2017
Abstract: Abstract. Changes in the depth of the freshwater–seawater interface in epishelf lakes have been used to infer long-term changes in the minimum thickness of ice shelves however, little is known about the dynamics of epishelf lakes and what other factors may influence their depth. Continuous observations collected between 2011 and 2014 in the Milne Fiord epishelf lake, in the Canadian Arctic, showed that the depth of the halocline varied seasonally by up to 3.3 m, which was comparable to interannual variability. The seasonal depth variation was controlled by the magnitude of surface meltwater inflow and the hydraulics of the inferred outflow pathway, a narrow basal channel in the Milne Ice Shelf. When seasonal variation and an episodic mixing of the halocline were accounted for, long-term records of depth indicated there was no significant change in thickness of ice along the basal channel from 1983 to 2004, followed by a period of steady thinning at 0.50 m a−1 between 2004 and 2011. Rapid thinning at 1.15 m a−1 then occurred from 2011 to 2014, corresponding to a period of warming regional air temperatures. Continued warming is expected to lead to the breakup of the ice shelf and the imminent loss of the last known epishelf lake in the Arctic.
Publisher: American Geophysical Union (AGU)
Date: 28-06-2021
DOI: 10.1029/2020JC016975
Abstract: Understanding the impact of the break‐up of northern Ellesmere Island ice shelves on fjord dynamics is limited by a lack of ocean observations prior to ice loss. Based on profiling and mooring data collected between 2011 and 2019, we describe the oceanography of Milne Fiord prior to the 2020 breakup of the Milne Ice Shelf, including, sources of ambient water, under‐ice hydrography, glacial modification, and seasonality. Ambient waters originate in the Canada Basin but are modified by interaction with the 100 m thick ice shelf at the fjord entrance, and extensive glacier tongue at the head. Properties within the 436 m deep fjord are depth‐dependent, with freshwater surface runoff and subglacial discharge accumulating in the upper 50 m of the fjord each summer behind the ice shelf. Freshwater export is restricted to a basal channel in the ice shelf, resulting in the fjord being more stratified and warmer than waters offshore year‐round. Below the ice shelf and above a 260 m deep sill unrestricted exchange allows warm Atlantic Water to penetrate to the 150 m deep glacier grounding line where submarine melting occurs. Basal meltwater spreads down‐fjord close to its depth of origin due to the strong stratification. Interannual warming of fjord deepwater is likely driven by shoaling of the Arctic Ocean thermocline and spillover at the sill, highlighting the link between fjord properties and regional oceanography. Further breakup of the ice shelf is predicted to substantially alter fjord dynamics, with consequences for ocean forcing of the Milne Glacier.
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