On the difficulty of modeling Circumpolar Deep Water intrusions onto the Amundsen Sea continental shelf

In the Amundsen Sea, warm Circumpolar Deep Water (CDW) intrudes onto the continental shelf and flows into the ice shelf cavities of the West Antarctic Ice Sheet, resulting in high basal melt rates. However, none of the high resolution global models resolving all the small ice shelves around Antarcti...

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Bibliographic Details
Published in:Ocean Modelling
Main Authors: Nakayama, Yoshihiro, Timmermann, Ralph, Schröder, Michael, Hellmer, Hartmut
Format: Article in Journal/Newspaper
Language:unknown
Published: Elsevier 2014
Subjects:
Antarctic
West Antarctica
Amundsen Sea
West Antarctic Ice Sheet
Bear Peninsula
Antarc*
Antarctica
Ice Sheet
Ice Shelf
Ice Shelves
Iceberg*
Pine Island
Sea ice
Online Access:https://epic.awi.de/id/eprint/36521/
http://www.sciencedirect.com/science/article/pii/S1463500314001383
https://hdl.handle.net/10013/epic.44341
Description
Summary:In the Amundsen Sea, warm Circumpolar Deep Water (CDW) intrudes onto the continental shelf and flows into the ice shelf cavities of the West Antarctic Ice Sheet, resulting in high basal melt rates. However, none of the high resolution global models resolving all the small ice shelves around Antarctica can reproduce a realistic CDW flow onto the Amundsen Sea continental shelf, and previous studies show simulated bottom potential temperature at the Pine Island Ice Shelf front of about −1.8 °C. In this study, using the Finite-Element Sea ice–ice shelf-Ocean Model (FESOM), we reproduce warm CDW intrusions onto the Amundsen Sea continental shelf and realistic melt rates of the ice shelves in West Antarctica. To investigate the importance of horizontal resolution, forcing, horizontal diffusivity, and the effect of grounded icebergs, eight sensitivity experiments are conducted. To simulate the CDW intrusion realistically, a horizontal resolution of about 5 km or smaller is required. The choice of forcing is also important and the cold bias in the NCEP/NCAR reanalysis over the eastern Amundsen Sea prevents warm CDW from intruding onto the continental shelf. On the other hand, the CDW intrusion is not highly sensitive to the strength of horizontal diffusion. The effect of grounded icebergs located off Bear Peninsula is minor, but may act as a buffer to an anomalously cold year.

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