The mission to rescue moorings in the Beaufort Sea that had to be planned on short notice, has succeeded! All three moorings hold scientific instruments and data recorded for the CAATEX project since September 2019. They have been picked up by Hanne Sagen, her team, and the KV Svalbard crew under extremely harsh Arctic conditions.

On October 15^th, Hanne Sagen and Espen Storheim from NERSC and other CAATEX-researchers left mainland Norway onboard the Norwegian Coast Guard ice breaker KV Svalbard. With them is the highly skilled KV Svalbard crew to enable this valiant endeavor – Sailing 5700 nautical miles to rescue equipment under extremely harsh conditions in the Arctic. Background information about the project and this extraordinary rescue mission can be found in a news story written by Hanne Sagen herself, from the 30.10.2020: Rescuing important ocean climate observations for the Coordinated Arctic Acoustic Thermometry Experiment (CAATEX).

Overview of the route to SIO 1 and the placement of the three moorings in the Beaufort Sea: Image: KV Svalbard

What is CAATEX and why did the moorings have to be rescued?

The CAATEX project – Coordinated Arctic Acoustic Thermometry Experiment – is aiming to make climate observations in the Arctic. The objective is to observe the water temperature in the Arctic Ocean below the sea ice over the course of a year and comparing them to similar measurements from experiments in the 1990’s. Moorings – a series of acoustic and oceanographic instruments on a long steel cable reaching from just below the ocean surface down to the sea floor – were set out in 2019 on both sides of the Arctic Ocean. Norwegian researchers led by Hanne Sagen (NERSC) set out four moorings in the Barents Sea North of Svalbard, and the American team placed three moorings in the Beaufort Sea North of Alaska. The Norwegian moorings were picked up in the summer of 2020, after recording data for one year, and the American moorings were supposed to get picked up by the American team. But due to a fire onboard the ice breaker USCGC Healy, this mission was cancelled. The Norwegian team and the Norwegian Coast Guard came together to retrieve the three remaining moorings in the Beaufort Sea before the winter to prevent data loss, which would endanger the entire project.

How are moorings in the Arctic picked up from below the sea ice?

The first step in mooring recovery is that the researchers find the exact position of the mooring below the sea ice from acoustic signals. Then the icebreaker starts to break up the ice in the area where the mooring is estimated to come to the surface. After sending the release signal the mooring is detached form the anchor and rises to the surface. The mooring buoy becomes visible and can be attached to the ship crane and the whole mooring is hoisted on deck.

Avalanche beacon search for the mooring buoy of SIO 3 at night when there is light in the Beaufort Sea: Photo: KV SvalbardRescuing mooring SIO 1

Over two weeks after leaving Norway and sailing north of the Russian coast along the sea ice edge, KV Svalbard reached the position of the first CAATEX-mooring, SIO 1. That is the northernmost mooring, placed north of 80°N. The preparation began on November 1^st, and the recovery process began the next day. After eight hours working on deck with wind chills of down to -36 °C, every piece of equipment was taken off the almost 4 km long cable. Difficulties occurred due to changes in drift, but the very experienced crew managed to work under these problematic conditions and the first mooring was recovered successfully.

Diver in the freezing cold water of the Beaufort Sea, getting ready to find the mooring buoy below the sea ice surface: Photo: KV SvalbardRescuing mooring SIO 2

Within a few days, KV Svalbard made its way through the Arctic sea ice and reached the position of the second mooring, SIO 2, south of 80°N. On November 5^th it was recovered. The weather conditions were much nicer, and the retrieval process took much less time.

The diver localized the mooring buoy, 20 m from the hole in the ice he went down in: Photo: KV SvalbardRescuing mooring SIO 3

Further south is the position of the last mooring, SIO 3. The researchers hoped for a quick and easy final recovery, but this mooring proved to be the most difficult of the three. The recovery process started on Monday, the 9^th of November. Since the ice was too thick for the mooring buoy to come to the surface, it got stuck below the sea ice. It was a real challenge for the crew to find the mooring buoy which was sitting under the ice somewhere close to the vessel. The solution was to use a diver who swam under the ice where he found the mooring buoy. The rest of the day and the following night was spent cutting a hole into the ice for so the crane could grab the mooring and hoist it onboard with all the valuable instruments. Everyone onboard KV Svalbard was relieved when things finally went according to plan and the third mooring was recovered completely in the early morning hours of the 11^th of November. The cold temperatures of down to -35 °C with wind chills made the recovery process extremely arduous, and the team onboard KV Svalbard deserves a lot of praise for a job well done! 

The mooring buoy of SIO 3 finally appeared on the surface!: Photo: KV SvalbardAnd now?

Now KV Svalbard is on the way back to Norway, and the researchers and crew members are scheduled to arrive in Longyearbyen on the 25^th of November. Hanne Sagen and her colleagues will spend the long way home investigating the data from the recovered moorings.

Selected media reports in Norwegian news papers about the rescue mission:

NRK 12.11.2020: Unike klimadata frå Polhavet redda etter kamp mot klokka

TV2 08.11.2020: Norge hjalp USA da de fikk problemer

TV2 16.10.2020: Seiler 5700 nautiske mil for å redde viktig klimadata

A full list can be found under "NERSC in media"