Skip to main content

Modelling Ice-shelf Melting and ice-Ocean Processes via the phase-field method and direct numerical simulation

Periodic Reporting for period 1 - MIMOP (Modelling Ice-shelf Melting and ice-Ocean Processes via the phase-field method and direct numerical simulation)

Reporting period: 2018-08-30 to 2020-08-29

The melting of ice shelves around Antarctica has been increasing in recent years, such that the Antarctic Ice Sheet is flowing more and more rapidly into the ocean and thinning. The thinning of the AIS is a key contributor to sea-level rise, such that predicting accurately ice-shelf melt rates is important to future policies on coastal use, protection and housing.
To dates, most climate models have some knowledge of the mean ocean temperature but do not have precise estimates for the ocean heat flux at the base of the ice, which controls melt rates.
As a result, climate scientists rely on empirical heat and salt transport coefficients, or transfer functions, which relate the ocean heat flux at the ice base to the resolved mean ocean temperature and currents, in order to estimate melting. The problem is that the heat and salt transport coefficients are poorly constrained, due to the lack of observations and high-fidelity simulations, such that predicted melt rates can be wrong by up to orders of magnitude.

The Marie Curie project MIMOP (Modelling Ice-shelf Melting and ice-Ocean Processes) was designed to bridge the gap between our need for accurate melt rate predictions and the lack of high-fidelity models and simulations of ice-shelf melting in polar oceans.
The first key objective was to derive a fully-coupled ice-ocean model able to resolve the full ocean dynamics and deformation of the ice-ocean interface.
The second key objective was to run as many simulations as possible of this model in order to gain new insights on the link between mean ocean temperature and basal heat fluxes.
The third key objective was to combine simulation results with field data in order to provide clear constraints on how to choose the transport coefficients based on the mean ocean temperature and currents.
Over the two years of the project, we have made significant progress toward the initial objectives of the project. We have:
a) developed a fully-coupled ice-ocean model able to resolve the full ocean dynamics and deformation of the ice-ocean interface,
b) run a number of simulations of boundary layer flows adjacent to an ice layer,
c) gained new insights into the physical processes controlling melting and the generation of topography at the ice-ocean interface,
d) investigated in details the interactions between the Antarctic Ice Sheet and subglacial lakes, which is a key example of ice-water interactions, in order to further shed light on the importance of turbulence on the ice-water boundary layer dynamics and on the relationship between the heat flux at the ice base, the mean water temperature and the turbulence intensity.

We have shared our results with the broad scientific community. I have submitted one paper on a),b),c) and two papers on d) as 1st author to peer-reviewed journals (total of 3 papers submitted as 1st author), and two papers on a),b),c) as co-author to peer-reviewed journals (total of 2 papers submitted as co-author). I have also communicated the project results at invited seminars (UC Berkeley, Feb 2020; LPG Nantes, Dec 2019; LEGI Grenoble, Oct 2019; Ladhyx Palaiseau, Mar 2019; U of Oxford, Mar 2019; U of Leeds, Feb 2019; U of Cambridge, Oct 2018) and conferences (2 presentations at EGU 2020; Ocean Sciences 2020; FRISP 2019; APS DFD 2018). I have also contributed to disseminating polar science to children in a local school during one science activity organised by the British Antarctic Survey.

Importantly, the simulations of the project were made possible thanks to a supercomputer allocation provided by PRACE, the Partnership for Advanced Computing in Europe. We acknowledge PRACE for awarding us access to Marconi at CINECA, Italy.
The MIMOP project has demonstrated the possibility to conduct high-fidelity simulations of ice melting, opening the way for a rigorous approach to predicting melt rates in the environment. We have highlighted a numerical procedure, which, for the first time, can resolve the full turbulent ocean dynamics and the evolution of the ice-ocean interface through melting and freezing. The expected results of the action include two publications as first author and two publications as co-author on key dynamical processes of boundary layer flows impacting melting and the generation of topography at the ice-ocean interface, and two publications on the related topic of water circulation in Antarctic subglacial lakes.

Future results of numerical simulations based on the method developed during the action will be key to constraining the heat and salt transport coefficients and improving melting estimates in Climate Models. Thus, the potential impact of the action's results is that it will significantly improve the reliability of sea-level rise predictions and changes to the large-scale ocean circulation due to enhanced melting of Antarctic ice.

The action has had a significant impact on my career, as it has helped me secure a faculty job in a research-leading university. I am now an assistant professor of physics at The University of Lyon and a research member of ENS de Lyon. This new position provides me with the opportunity to continue the work I have started as a MSCA fellow within a research-intensive institute. The MSCA fellowship has helped me gain expertise in the problem of ice-ocean interactions and a wide network of collaborators in the US, the UK, France, and Australia, which will help me be competitive in future European grant competitions. Ultimately, the MSCA fellowship has provided me with a first step toward reaching a worldwide leadership position on ice-ocean interactions, which play a major role in Climate Change but also on the possibility to discover lifeforms outside of Earth, i.e. in icy moons and planets, such as Enceladus and Europa, which are regarded as prime astrobiology targets.