Seasonal variations in meltwater from Pine Island Ice Shelf
Abstract
The recent acceleration in ice mass loss from Pine Island Ice Shelf in the Amundsen Sea, Antarctica, is widely attributed to ocean forcing. Monitoring the outflow of meltwater from the ice cavity into the surrounding ocean is challenging because the region is very remote and accessible for ships only in summer, and moorings have to keep several hundred meters below the surface to avoid icebergs, so little is known about the near surface ocean evolution in winter. Here we present the first wintertime estimates of ice shelf meltwater along the front of Pine Island Ice Shelf obtained from profiles of temperature and salinity from sensors on elephant seals and Weddell seals which spent the winter diving to near the bottom in the area near the glacier. A comparison of the seal-derived hydrographic section in August 2014 with that obtained from ship-based measurements in February 2014 reveals a significant change of water properties and corresponding change of glacial meltwater content. A slightly fresher layer detected between 300-700 m in winter suggests a greater meltwater content. The meltwater content shows a distinct maximum at ~450 m in winter, below the cold Winter Water above, whereas in summer the meltwater is more difficult to distinguish from the warmer water above without the use of additional tracers. Due to the lack of surface heating in these wintertime observations, we robustly quantify the near-surface meltwater outflow. We discuss the temporal and spatial differences in the meltwater layer along the ice shelf front. The results may be compared with analogous meltwater calculations from seals tagged in February 2019.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C13A..03H
- Keywords:
-
- 0720 Glaciers;
- CRYOSPHERE;
- 0726 Ice sheets;
- CRYOSPHERE;
- 0728 Ice shelves;
- CRYOSPHERE;
- 4207 Arctic and Antarctic oceanography;
- OCEANOGRAPHY: GENERAL