The Amundsen Sea Expedition 2017- 2018 (ANA08B): IBRV Araon, 21 December 2017 -13 February 2018 (Christchurch to Christchurch, New Zealand)

Abstract

In order to monitor the temporal and spatial variation of circumpolar deep water (CDW) and its effect on the rapid melting of glaciers in the Amundsen Sea and Udintsev Fracture Zone (UFZ), an extensive oceanographic survey was conducted on the 2018 expedition (ANA08B). The overall aims in the field of physical oceanography were: (1) to identify the temporal and spatial variation of Circumpolar Deep Water (CDW) and (2) to estimate the effect of meltwater from glaciers on the ocean circulation. During - 4 - the 2018 cruise (ANA08B) by IBRV Araon, a total of 53 CTD stations were visited. In UFZ, two moorings which installed in 2016 were recovered but one mooring was lost. Five KOPRI moorings were successfully recovered and 4 moorings were deployed again on the shelf troughs and near the ice shelf fronts. UGOT and UIB moorings placed at the western side of Getz Ice Shelf between Siple and Dean Islands and Siple and Carney Island during ANA06B was installed and recovered during ANA08B. Three moorings of UGOT was installed again at the western side of Getz Ice Shelf to study the ocean circulation in the Getz Ice Shelf cavity. Another element of the cruise was The Ocean Robots Beneath Ice Shelves (ORBIS) program, funded by the Paul G. Allen Family Fundation, and involving the University of Washington and Columbia University. This program aimed at developing technologies to observe the ocean cavities beneath the ice shelves over long periods of time (few months to one year), using Seagliders, float profilers and RAFOS beacons for under ice acoustic navigation. Preliminary results are exceptionally encouraging. In order to understand the evolution of West Antarctic Ice Sheet and assess glacier sensitivity to ocean warming and climate change, the aero-geophysical observations was operated during ANA08B over floating and grounded glacier ice along the Amundsen Sea Coast. On the other hand, two ApRES units were deployed on ANA08B, on the eastern side of Getz Ice Shelf and a total of six T-POP units were deployed at two separate sites on ANA08B. Additional, a total of 20 drifters were deployed between Udintsev Fracture Zone and Amundsen Sea.