Emperor penguin

Emperor penguin. Photo: Christian Stranne

The ocean freshwater balance of the Antarctic shelves is currently changing, at least partly in response to the surging and melting of the West Antarctic Ice Sheet (WAIS). The
most dramatic thinning of the WAIS has been recorded in several glaciers feeding the ice shelves in the Amundsen Sea. Understanding the ocean circulation in this area is central to our ability to predict the behaviour of the WAIS, the melting of which can in turn affect the global sea level. Antarctica is surrounded by a comparatively warm and salty oceanic water mass, the Circumpolar Deep Water (CDW), which has a temperature of 1–2 °C. This project will use in situ measurements, remote sensing, and modelling to study the flow of CDW on the Amundsen Shelf, and the subsurface melting of icebergs and ice shelves that it induces.

The specific goals of the project are:

  1. to identify the forcing mechanisms underlying the flow of CDW onto the shelf, and
  2. to characterize the time variability and trends in the CDW flow and compare these to time series of the forcing mechanisms.
Icebreaker Araon

Icebreaker Araon in the Amundsen Sea. Photo: Christian Stranne

To achieve these goals, we have serviced and redeployed three subsurface moorings (see figure) in the central Amundsen Shelf. The moorings are part of an international collaboration to monitor the CDW and associated rapid melting of glaciers in the Amundsen Shelf. Four institutions from South Korea, Great Britain, USA, and Sweden are working together in a resource-sharing programme. During the 2012 Amundsen Sea cruise on the Korean icebreaker Araon, 16 moorings were successfully recovered and 15 moorings were deployed at the shelf break, at shelf troughs, and near the floating glacier fronts. The recovered data will be shared via the public National Oceanographic Data Center database and the Southern Ocean Observing System database.

Mooring profile

Mooring profile.

The first scientific results of the project have been published in three international peer-reviewed papers. Two additional papers have been submitted and two more are currently in preparation.

We would like to express our gratitude to the Korea Polar Research Institute, for their logistical support.