With an extraordinary rescue operation the crews of the two cruise ships MV Plancius and MV Ortelius managed to recover unmanned remote controlled seagliders in the Greenland Sea a few days ago. With this action, Oceanwide Expeditions helped the oceanographer Dr. Katrin Latarius from AWI to successfully complete a scientific measurement program in the Greenland Sea. Oceanwide Expeditions adjusted its routes for the search of the seagliders. The ships stopped in the open sea, the crews were launching inflatable Zodiac boats into the water in order to rescue the two autonomous underwater vehicles of AWI out of the water.

The recovered Seaglider on board of the M/V Plancius. Since 2008, the Alfred-Wegener-Institute uses submerged seagliders for oceanographic measurements in the Northern Fram Strait. Photo: Katja Riedel
The recovered Seaglider on board of the M/V Plancius. Since 2008, the Alfred-Wegener-Institute uses submerged seagliders for oceanographic measurements in the Northern Fram Strait. Photo: Katja Riedel

The instruments have been deployed beginning of July during an expedition of Research Vessel Polarstern. The gliders with a length of two meters repeatedly dived to 1000 m depth along given sections and measured temperature, salinity and oxygen on the way. When reaching the surface the data were send via satellite to the AWI in Bremerhaven. Thus the scientists have access to the data in real time. This way of communication was used by the scientists to adjust the cruise track – for example when the glider was approaching the ice-edge off Greenland.

Captain Alexey Nazarov of the Plancius with seamen looking for the seaglider Photo: Jerry Xu
Captain Alexey Nazarov of the Plancius with seamen looking for the seaglider Photo: Jerry Xu

The data, gathered during the mission, will be used by Katrin Latarius, to analyze the effect of increasing freshwater in the near-surface layer of the Arctic on the deep water renewal in the Nordic Seas. Backgrounds of this question are changes in the climate of the Arctic Ocean: Sea-Ice melt, elevated river-runoff as well as precipitation lead since the 1990th to increased near-surface freshwater content in the Arctic. From there the freshwater spread out in direction to the North Atlantic. As freshwater stabilizes the stratification in the water column, it hampers the sinking of cooled water to great depths. Thus the scientists from AWI assume, more freshwater will also reach the inner Nordic Seas and will hamper the deep water ventilation there. First results are expected in the coming weeks.

The seagliders can operate for 9 months doing approximately 740 dives down to 1’000 meters.
The seagliders can operate for 9 months doing approximately 740 dives down to 1’000 meters.

Source: The Arctic Journal, http://arcticjournal.com