Norwegian-Canadian collaboration in the Circumpolar Flaw Lead System Study

The Circumpolar Flaw Lead System Study (CFL) is a large Canadian-led international effort to understand the role of the CFL in a context of Arctic warming.

Dykking

Photo: H.Hop / Norsk Polarinstitutt

Dykkerteamet

Diver team besides CCGS Amundsen, ready to go in the skippy boat to the dive hole. From left: Jeremy Stewart (DFO-dive leader), David Barber (CFL-project leader) and Haakon Hop (NPI-research diver). Photo: H. Hop / Norwegian Polar Institute, J. Stewart / DFO

Dykkerteamet klare for dykking

Dive team getting ready for diving below the ice. Divers Haakon Hop (left) and Jeremy Stewart (right).  Ice physicist Jens Ehn (middle) gives advice on the light measurements. Photo: H. Hop / Norwegian Polar Institute, D. Barber

MÃ¥lelinje

Ice physicists Jens Ehn (Univ.Manitoba) and Cristopher J. Mundy (Univ.Quebec) set up a measuring transect across a melt pond on the ice. Photo: H. Hop / Norwegian Polar Institute

Haakon Hop diving with rebreather below the sea ice. Photo: H. Hop / Norsk Polarinstitutt, J. Stewart / DFO

Iskrystaller og smeltevannslag

Ice platelets and melt layer below Arctic sea ice. The melt layer can be seen below. Photo: H. Hop / Norsk Polarinstitutt

Smeltevannslag

A thick (40-50 cm) meltwater layer formed below the Arctic sea ice during spring. Photo: H. Hop / Norsk Polarinstitutt

Dykkehull

Line tender Dave waiting for his Norwegian ice diver. Photo: H. Hop / Norsk Polarinstitutt

CFL-Logo

This project has been the largest of any International Polar Year projects, and has involved the use of the Canadian research icebreaker CCGS Amundsen during almost a year in the icy waters of Arctic Canada.

The research projects involved a broad multidisciplinary effort to study melting processes in Arctic sea ice during spring. Marine ecologists and ice physicists worked closely together to study the effects of incoming solar radiation on melting processes and marine life below land-fast ice in Darnley and Franklin Bays of the Amundsen Gulf. During the spring, melt ponds develop and changes the reflective properties of sea ice dramatically. Less light gets reflected and more absorbed by the darkened surfaces. Melt ponds act as windows in the ice and cause melting and development of domes on the ice under-surface.

Norwegian Polar Institute senior researcher Haakon Hop participated in this study by measuring light below the sea ice. He is a research diver, with extensive experience in under-ice diving in the Arctic, and dove with semi-closed rebreather below the ice to minimize release of bubbles during light measurements. Even if the ice is melting fast, the water temperature is still below zero, so he needed to use thick neoprene dive suit to withstand the cold.

A multispectral radiometer (light meter that can measure many wave lengths) was used to measure light along a line above and below the melt pond. The depth of melt ponds as well as the elevation of the dome below was also measured. During spring, the meltwater layer developed to more than 50 cm, and there was a clear division against the more saline water below.

Ice algae covered the underside of the ice in March, when senior research scientist Stig Falk-Petersen and Anette Wold (NPI) participated in the CFL-project on CCGS Amundsen. The ice algae disappeared during the spring melt and were gone by June, when our studies of melting processes were performed. However, the yellow ice amphipods still resided in the brine channels below the ice even though their main food source of ice algae were absent. The diver used an electrical suction pump and a frame that is placed below the ice to sample them quantitatively. Mass samples of amphipods were also obtained for studies of contaminants, such as persistent organic pollutants and heavy metals. There was a thick layer of zooplankton right at the interface between the meltwater and the more saline water below, and these were sampled by swimming transects with frame nets. Presumably the remaining ice amphipods as well as juvenile polar cod feed on these zooplankton organisms, when they come close to the under-surface of the ice.

This project has served as a prime example of a fruitful multidisciplinary study of Arctic sea ice. The results will be presented during an upcoming CFL-meeting in Winnipeg, Canada, in 2009. For more information, please check the CFL-web. The project has been carried out within the research networks Arctic Net and ARCTOS which are coordinated by the IPY-project PAN-AME.