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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, C10019, doi:10.1029/2006JC003733, 2007

Numerical modeling of ocean-ice interactions under Pine Island Bay's ice shelf

Antony J. Payne

Centre for Polar Observation and Modelling, University of Bristol, Bristol, UK


Paul R. Holland

British Antarctic Survey, Cambridge, UK
Centre for Polar Observation and Modelling, University College London, London, UK


Andrew P. Shepherd

Centre for Polar Observation and Modelling, University of Cambridge, Cambridge, UK


Ian C. Rutt

Centre for Polar Observation and Modelling, University of Bristol, Bristol, UK


Adrian Jenkins

British Antarctic Survey, Cambridge, UK


Ian Joughin

Polar Science Centre, University of Washington, Seattle, Washington, USA


Abstract

A two-dimensional numerical model is used to simulate the dynamics of buoyant, meltwater-rich plumes flowing beneath the ice shelf occupying much of Pine Island Bay, West Antarctica. Recent studies have shown that this ice shelf, along with all others fringing the Amundsen Sea, is thinning rapidly. In the model, both the Coriolis effect and subshelf topography are important in controlling plume dynamics and the spatial distribution of ice melt. Melt is concentrated in a narrow zone within ∼20 km of the grounding line where steep subshelf slopes and access to warm ambient water allow melt rates to exceed 100 m yr−1. The plume generated by entrainment of ambient water into the meltwater in these areas is guided by the topography of the ice shelf underside and exits the ice shelf at three distinct outflow locations. Melt rates generated along the course of the plume are higher (approximately 2.5×) than rates elsewhere. The model suggests that the observed ice shelf thinning rates could have resulted from a hypothetical instantaneous 0.25°C warming of the ambient water entrained by the plume. A context for this value is provided by the 40-year warming trend documented by Jacobs et al. (2002) for Circumpolar Deep Water in the nearby Ross Sea.

Received 26 May 2007; accepted 2 August 2007; published 19 October 2007.

Keywords: Antarctica; ice shelf; climate variability.

Index Terms: 0776 Cryosphere: Glaciology (1621, 1827, 1863); 0728 Cryosphere: Ice shelves; 4255 Oceanography: General: Numerical modeling (0545, 0560); 4562 Oceanography: Physical: Topographic/bathymetric interactions; 4217 Oceanography: General: Coastal processes.

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Citation: Payne, A. J., P. R. Holland, A. P. Shepherd, I. C. Rutt, A. Jenkins, and I. Joughin (2007), Numerical modeling of ocean-ice interactions under Pine Island Bay's ice shelf, J. Geophys. Res., 112, C10019, doi:10.1029/2006JC003733.