Project 4287

Preparing for the impacts of sea-level rise needs an improved understand of the response of the Antarctic Ice Sheet to changing ocean conditions. Over the last decade it has become clear that more ocean driven melting beneath ice shelves is causing the Antarctic Ice Sheet to lose ice at an increasing rate, contributing to sea-level rise. This project will explain the role of the ocean in controlling this dynamic behavior of the Antarctic Ice Sheet. We will use state-of-the-art numerical modelling and available observations to determine the key processes that control the mass budget of ice shelves and how the Antarctic ice flows into the oceans, together with the assessment of the scale of possible future change. This proposal will provide improved understanding of the processes controlling ice sheet and sea level and will help to provide realistic estimates of freshwater and heat transport in a global ocean context.

As an Australian-based project, the development and application of the numerical models has occurred throughout the year. Several key milestones have been achieved, most notable is the initial coupling between the Regional Ocean Modeling system (ROMSIceShelf) and an Ice Sheet model (Elmer/ice) using a new Framework for Ice Sheet and Ocean Coupling (FISOC), based on the Earth System Modeling Framework (ESMF). Simulations using several different idealised and regional ice sheet and ocean model domains were also completed and published.

The continued development and application of the numerical models has occurred throughout the year, resulting in several publications in international peer-reviewed journals. Several key milestones have been achieved, most notable is the initial coupling between the Regional Ocean Modeling system (ROMSIceShelf) and an Ice Sheet model (Elmer/ice) using a new Framework for Ice Sheet and Ocean Coupling (FISOC), based on the Earth System Modeling Framework (ESMF). Simulations using several different idealised and regional ice sheet and ocean model domains were also completed and published.

In 2016/17 a variation to the project was approved to deploy GPS and Autonomous phase-sensitive Radio Echo Sounding (ApRES) instruments on the Totten Glacier. The field work was successful resulting in the first acquisition (of about 5-14 days) of GPS and ApRES data from 6 locations straddling the deepest part of the grounding zone. Results provide first ground-based estimates of the basal melting of the ice shelf together with ice dynamics and flow. Furthermore, the deployments were made to overwinter and will be collected next season (2017/18), with the APrES units continuing to broadcast a daily compressed data stream via Iridium satellite that will provide understanding about how the glacier/ocean system changes. These data will be used to evaluate the numerical models being developed in this project.

The continued development and application of the numerical models has occurred throughout the year, resulting in several publications in international peer-reviewed journals. Several key milestones have been achieved, including the first comparisons between models and observations for the Totten Glacier region, a key outlet glacier in East Antarctica. First results from a pan-Antarctic ice-shelf/ocean model have been completed to eventually be coupled with a whole-Antarctic ice sheet model. Simulations using several different idealised and regional ice sheet and ocean model domains were also completed and published.

In 2017/18, together with AAS4436 - Totten Ice Dynamics and Evolution - data was recovered from GPS and Autonomous phase-sensitive Radio Echo Sounding (ApRES) instruments on the Totten Glacier. The field work was successful resulting in the first acquisition of more than 13 months data from six locations straddling the deepest part of the grounding zone. The towers were also refurbished to continue logging for another year to be recovered next season (2018/19). The ApRES units continue to broadcast a daily compressed data stream via Iridium satellite that will provide understanding about how the glacier/ocean system changes. These data will be used to evaluate the numerical models being developed in the project.

The continued development and application of the numerical models has occurred throughout the year. Whole ice sheet simulations using Elmerice in preparation for coupling to the ocean model are also contributing to the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) designed to provide ensembles of future projections of changes to the ice sheets and contribute to answering the World Climate Research Programme (WCRP) Grand Challenges on 'Melting Ice & Global Consequences' and 'Regional Sea-Level Change & Coastal Impacts'. Simulations using several different idealised and regional ice sheet and ocean model domains were also completed and published. In 2018/19, together with AAS4436 - Totten Ice Dynamics and Evolution - data was recovered from GPS and Autonomous phase-sensitive Radio Echo Sounding (ApRES) instruments on the Totten Glacier. The field work was successful resulting in the final successful collection of about 2 years data from six locations straddling the deepest part of the grounding zone. These data will be used to evaluate the numerical models being developed in the project and will feed directly into a newly established international initiative called Realistic Ice-sheet/ocean State Estimates (RISE). RISE will function to coordinate rapid advances in modelling and observations of ocean-driven melting of the Antarctic Ice Sheet and is endorsed by the Southern Ocean Observing System (SOOS) and the International Union of Geodesy and Geophysics.

This project has made pioneering advances in the development and application computational software designed to predict the response of the ice sheet to ocean warming. Most notable is the coupling between the Regional Ocean Modeling system (ROMSIceShelf) and an Ice Sheet model (Elmer/ice) using a new Framework for Ice Sheet and Ocean Coupling (FISOC), based on the Earth System Modeling Framework (ESMF). Whole ice sheet simulations using Elmer/ice in preparation for coupling to the ocean model are also contributing to the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) has resulted in the publication of several important papers to be included in the next IPCC. These experiments were designed to provide ensembles of future projections of changes to the ice sheets and contribute to answering the World Climate Research Programme (WCRP) Grand Challenges on 'Melting Ice & Global Consequences' and 'Regional Sea-Level Change & Coastal Impacts'. Simulations using several different idealised and regional ice sheet and ocean model domains were also completed and published. In 2016/17 a variation to the project was approved to enable an intensive field campaign to understand the Totten Glacier, one of the fastest changing regions in Antarctica. In 2018/19, together with AAS4436 - Totten Ice Dynamics and Evolution - data was recovered from GPS and Autonomous phase-sensitive Radio Echo Sounding (ApRES) instruments on the Totten Glacier. The field work was successful resulting in the final successful collection of about 2 years data from six locations straddling the deepest part of the grounding zone. These data will be used to evaluate the numerical models being developed in the project and will feed directly into a newly established international initiative called Realistic Ice-sheet/ocean State Estimates (RISE) that will continue under the Australian Antarctic Program Partnership (AAPP). RISE will function to coordinate rapid advances in modelling and observations of ocean-driven melting of the Antarctic Ice Sheet and is endorsed by the Southern Ocean Observing System (SOOS) and the International Union of Geodesy and Geophysics (IUGG).