Modeling Ocean Circulation and Ice Shelf Melt in the Bellingshausen Sea

Abstract

The ice shelves in the Bellingshausen Sea are melting and thinning rapidly due to modified Circumpolar Deep Water (mCDW) intrusions carrying heat toward ice‐shelf cavities. Observations are, however, sparse in time and space, and extensive model‐data comparisons have never been possible. Here, using a circulation model of the region and ship‐based observations, we show that the simulated water mass distributions in several troughs traversing mCDW inflows are in good agreement with observations, implying that our model has the skills to simulate hydrographic structures as well as on‐shelf ocean circulations. It takes 7.9 and 11.7 months for mCDW to travel to the George VI Ice Shelf cavities through the Belgica and Marguerite troughs, respectively. Ice‐shelf melting is mainly caused by mCDW intrusions along the Belgica and Marguerite troughs, with the heat transport through the former being ∼2.8 times larger than that through the latter. The mCDW intrusions toward the George VI Ice Shelf show little seasonal variability, while those toward the Venable Ice Shelf show seasonal variability, with higher velocities in summer likely caused by coastal trapped waves. We also conduct particle experiments tracking glacial meltwater. After 2 years of model integration, ∼33% of the released particles are located in the Amundsen Sea, supporting a linkage between Bellingshausen Sea ice‐shelf meltwater and Amundsen Sea upper ocean hydrography.

Pathways of Inter‐Basin Exchange From the Bellingshausen Sea to the Amundsen Sea

“…Furthermore, modeling studies show that glacial meltwater can trigger a positive feedback mechanism that enhances ice shelf melt through changes in ocean stratification at the ice shelf front (Flexas et al, 2022). Feedbacks between the different components of the freshwater balance and their role in modifying the shelf overturning circulation and ice shelf basal melt (e.g., Bett et al, 2020;Hyogo et al, 2024;Jourdain et al, 2017;Kimura et al, 2017;Moorman et al, 2023) are critical aspects that deserve further exploration, in particular in the Bellingshausen Sea.…”