Helicopter-based observations reveal warm ocean flows toward the Totten Ice Shelf in Southeast Antarctica.

An international team of scientists has successfully conducted a helicopter-based survey of the East coast of Antarctica and identified the pathways through which warm ocean water travels from the open ocean to the vents of the ice shelves for the first time.

During the six days of observations, the team was able to recover temperature and other data in 67 locations covering the entire continental shelf except the Totten Ice Shelf, the floating part of the Totten Glacier. The study allowed the team to get a complete picture of the warm seawater flowing through the ice core. This paper is published in a journal Geophysical Research Letters.

The Totten Glacier has attracted global attention because of the range of environmental impacts if the glacier were to melt completely: global sea levels could be raised by almost four metres. Therefore it is necessary to look at the whole area of ​​the continental shelf to understand the ways and means of inflow of warm water. However, that has historically been hindered by extreme sea ice and icebergs.

The team, including Assistant Professor Yoshihiro Nakayama and Associate Professor Shigeru Aoki of Hokkaido University’s Institute of Low Temperature Science, conducted a helicopter-based observation in cooperation with the Maritime Self-Defense Force of Japan as part of the 61st Japanese Antarctic Research Expedition (JARE61).

The researchers took a CH-101 helicopter from the icebreaker Shirase to the observation points where they dropped two types of observation sensors: AXCTD (Airborne Expendable Conductivity, Temperature, and Depth) and AXBT ( -Airborne Bathy-Thermograph). The team was able to investigate underwater temperatures and salinity using data from the sensors.

The team found that a wide oceanic heat wave—extending about 150 kilometers between longitudes 116.5° east and 120.5° east—was penetrating toward the shelf. Sea water with a temperature of about 1°C above freezing is found between 50 and 100 meters above sea level. This showed, for the first time, a complete picture of the mass of warm water flowing onto the Totten Ice Shelf.

This study also demonstrated the effectiveness of using helicopters in conducting such research. They are cheaper and faster than icebreakers, have excellent maneuverability and are not affected by sea ice conditions. Identified routes can be inspected in detail by icebreakers.