Modeling Ice Shelf Cavities and Tabular Icebergs Using Lagrangian Elements

• Published in: Journal of geophysical research. Oceans 2019-05, Vol.124 (5), p.3378-3392
• Main Authors: Stern, A. A., Adcroft, A., Sergienko, O.
• Format: Article
• Language: English
• Subjects: Antarctic ice; Antarctic ice shelves; calving; Climate models; Computer simulation; Drift; Flow simulation; Geophysics; Holes; Ice; Ice calving; Ice front; Ice fronts; ice shelf; ice shelf model; Ice shelves; iceberg; Iceberg calving; Icebergs; Instruments; kinematic ice dynamics model; Lagrangian model; Land ice; Mass balance; Ocean circulation; Ocean currents; Ocean models; Ocean surface; Ocean warming; Ocean-atmosphere system; Oceans; Sea level; Simulation; Water circulation; Water column; Water depth
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1029/2018JC014876

Most ocean climate models do not represent ice shelf calving in a physically realistic way, even though the calving of icebergs is a major component of the mass balance for Antarctic ice shelves. The infrequency of large calving events together with the difficulty of placing observational instruments around icebergs means that little is known about how calving icebergs affect the ocean. In this study we present a novel model of an ice shelf coupled to an ocean circulation model, where the ice shelf is constructed of Lagrangian elements that allow simulation of iceberg calving. The Lagrangian ice shelf model is used to simulate the flow beneath a static idealized ice shelf, to verify that it can reproduce the results of an existing Eulerian model simulation with an identical configuration. The Lagrangian model is then used to simulate the ocean's response to a calved iceberg drifting away from the ice shelf. The results show how a calving event and subsequent iceberg drift affect the ocean. At the ice front, the calving event leads to a warming of the ocean surface and cooling of the water column at depth, allowing cooler waters to enter the ice shelf cavity, leading to reduced melt rates within the cavity. A Taylor column is observed below the iceberg, which moves with the iceberg as it drifts into the open ocean. As the iceberg drifts further from the ice shelf, the circulation within the ice shelf cavity tends toward a new steady state, consistent with the new ice shelf geometry. Key Points A novel modeling framework is developed to simulate ice shelves calving icebergs using Lagrangian elements, held together by numerical bonds After an iceberg calves away from an ice shelf, a complex interaction is observed between the iceberg motion and ocean hydrography A Taylor column, subsurface cooling at the ice front, and reduced melt rates within the ice‐shelf cavity are observed after iceberg calving