Modeling Circumpolar Deep Water intrusion onto the Bellingshausen Sea continental shelf

Abstract:

The ice shelves and glaciers of the West Antarctic Ice Sheet are thinning rapidly in the Amundsen and Bellingshausen Seas. The high basal melt rate of these ice shelves is caused by warm Circumpolar Deep Water (CDW) that mainly intrudes via submarine glacial troughs located at the continental shelf break. Here, we conduct ocean simulation for a regional Amundsen and Bellingshausen Sea configuration of the Massachusetts Institute of Technology general circulation model (MITgcm). Model simulation is conducted between 1992-2018. Horizontal spacing is about 3 km and there are 70 vertical levels ranging thickness from 10 m near the surface to ~450 m near the bottom.

We evaluate our model by comparing it with exiting observations (ship-based and seal CTDs) to clarify our model's reproducibility. The simulated horizontal and vertical sections of temperature and salinity show a close agreement with the observation data for 2001-2016. Besides, the simulated time series of thermocline depth also show a reasonably good agreement.

Ocean heat transports through submarine glacial troughs towards ice shelves in the Bellingshausen Sea. Particle release experiments show that CDW intrudes along three troughs (Belgica, Lately, Margurite Trough) without strong seasonal variability. It takes ~9 months for these particles to travel over the continental shelf and flow into these ice shelf cavities. In this presentation, we will further show the time series of ocean heat content in each ice shelf cavities and discuss driving mechanisms of its temporal changes.