Sergei Kirillov, Dave Babb, Igor Dmitrenko
CEOS, University of Manitoba
Northern Greenland: One of the most severe regions on Earth where the ice pack remains intact year round and the harsh climate makes working, let alone living a constant battle. The area was first explored in the early 1900s as part of the Danmark expedition, which ended tragically, and remains uninhabited besides a small Danish contingent at the Station Nord military base and the Sirius dog sledge patrol. To this day there are large expanses of land and ocean that have never been visited; scientifically very little is known about the area.
Station Nord (81°36‘ N, 16°38’ W) is the second most northern permanent settlement on Earth, behind the Canadian airbase in Alert at the top of Ellesmere Island. The base is located in the northeast corner of Greenland, in an area where the outflow of the Greenland ice sheet from Danmark and Independence Fjords interact with the Weddell Sea and Fram Strait. The area is home to outlet glaciers and glacial tongues that calve off massive icebergs which remain locked into the landfast sea ice year round. The station was established in the 1950s as a weather station, but officially became a Danish military base in 1975. In 2014 Aarhus University opened the Villum Research Station, which houses world leading facilities to researchers interested in investigating the Arctic and the unique area of northeast Greenland. In April 2015 a group of 12 international scientists, six from the University of Manitoba, arrived for the first scientific leg at the Villum Research Station as part of the Arctic Science Partnership (ASP). The work was incredibly multidisciplinary, though the three of us (Sergei, Dave and Igor) focused on oceanographic and sea ice measurements from the surrounding landfast sea ice.
The priority of our project was to consider the physical processes (both oceanographic and atmospheric) that potentially impact the landfast sea ice and tidewater glaciers around Station Nord. It’s believed that relatively warm intermediate North Atlantic waters penetrate along the submarine troughs and valleys into the shallow coastal areas surrounding Station Nord from the intermediate depths off the NE Greenland continental slope. Heat from the North Atlantic waters can affect the stability of the glacial tongues and also affect sea ice growth and melt processes along the underside of the landfast ice cover. To accomplish our objectives we had a sampling plan to cover the spatial and temporal variability of the oceanography and sea ice around Station Nord. To cover the spatial variability we carried out multiple CTD transects during which we did a CTD cast every 2 km, while also continuously measuring sea ice and snow properties with a towed electromagnetic induction system. In total we did over 100 CTD casts, which not only revealed the local variability in water masses and identified a very fresh surface layer, but also proved useful in determining the local bathymetry since most of the area had not been surveyed previously. To cover the temporal scale we deployed sea ice tethered moorings, equipped with current profilers and CTD sensors, for a short-term deployment (three weeks) directly in front of the glacier and then for a long-term deployment (one year) on landfast sea ice with co-located ice mass balance buoys. The short term deployment provided high resolution observations on the glacial freshwater outflow and its effect on the vertical stratification near the mouth of the glacier. The long term deployment will provide information on the annual cycle of mixing, salinity and heat within the water column and then relate this to thermodynamic changes in the overlying ice, specifically ice growth and melt processes. The buoys also measure various surface atmospheric variables (air temperature, pressure, winds and snow depth) that are useful when considering the seasonal evolution of thermodynamics of the sea ice. The buoy also has a GPS that will be useful when recovering the instrumentation next year.
Beyond cold temperatures, high winds and blowing snow the work was complicated by the fact that there was on average 1-2 m of snow on top of the ice, which made for a lot of shoveling and wet boots, since the snow was causing a negative freeboard and surface flooding occurred everywhere. The vast amount of snow only slowed us down, whereas it prevented our colleagues looking at under ice algae from observing anything. Shoveling and drilling every hole took a lot of effort and none of this work could have been done without Kunuk and Ivali Lennert from the Greenland Climate Research Center who worked tirelessly to help in every way they could.
The local ice pack was a mix of first, second and multi-year sea ice, with greater coverage of older ice types that through tracking with satellite imagery, we know have been there for over 10 years. First year ice in the area averaged 1m depth, while the older ice types varied from 2m to 4m but generally hovered around an equilibrium thickness of approximately 3m. The idea of an equilibrium thickness is very interesting as it represents the equilibrium between summer melt and winter growth of the sea ice, which is of course a reflection of the heat supplied by the underlying water column. Observations from our yearlong deployment should provide more information on this.
A high resolution grid of snow depth, ice thickness and freeboard observations were made along a track previously flown by the NASA IceBridge project (www.nasa.gov/mission_pages/icebridge) and will be used to validate the airborne observations. The EM-31 system was used in conjunction with a snow probe to sample a 350m x 60m grid at 5m intervals, with manual drill hole measurements made every 25m to verify the EM observations and also to measure freeboard. Generally the first year ice was quite homogeneous averaging about 1.2m in thickness. Comparatively the multiyear ice was incredibly variable ranging from 2m to 4m across very small distances. The multiyear ice was rough from years of melt which forms melt ponds on the upper surface and under ice ponds, which very little is known about. Interestingly these ponds contained water that was completely fresh and drinkable. We also observed a thin frazil ice layer that formed at the bottom of this pond across the freshwater-saltwater interface. We are working up our observations from these ponds and will have some results to share in the not too distant future.
I think we all agree that our time at Station Nord was amongst the most difficult field work we have done. The conditions were harsh, the weather was rough and the work difficult; but the group of researchers, logistics personnel and military personnel made it one of the best field experiences we’ve had. Many thanks to the Danish military personnel (Kristian, Rune, Lasse, Mikael, Tommy and Smit) who kept the ‘streets’ at Nord clear of snow and the coordinators of the Villum Research Station who kept things running smoothly. We are back home now working up the data from this year, while also thinking of what our long-term observations will reveal when we return to recover the equipment next year. There is another group from ASP heading up to Nord during August for a summer campaign to supplement our observations and carry out other sampling routines. Open water and poor ice conditions will challenge them in the way that the cold weather, blowing snow and poor visibility challenged us.
Shoveling the snow for ice and ocean measurements (credit: Dave Babb).
Near one of the icebergs anchored in the multiyear landfast sea ice (credit: Dave Babb).
Igor Dmitrenko and Nicolas-Xavier Geilfus take the water samples for chemical analysis.
The deployment of Acoustic Doppler Current Profiler in the mooring position.