Representing grounding line migration in synchronous coupling between a marine ice sheet model and a z-coordinate ocean model

Goldberg, David M.; Snow, Kate; Holland, Paul R.; Jordan, James; Campin, Jean‐Michel; Heimbach, Patrick; Arthern, Robert; Jenkins, Adrian

doi:10.1016/j.ocemod.2018.03.005

Cited by 25 publications

(37 citation statements)

References 62 publications

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“…The following three parameterisations are based on an expression for the ice-ocean heat transfer that is analogous to the one used in more complex ocean circulation models (Grosfeld et al, 1997). However, they make the simplifying assumption that the thermal forcing across the iceocean boundary layer can be determined directly from farfield ocean conditions.…”

Section: Simple Functions Of Thermal Forcingmentioning

confidence: 99%

Assessment of sub-shelf melting parameterisations using the ocean–ice-sheet coupled model NEMO(v3.6)–Elmer/Ice(v8.3)

et al. 2019

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Abstract. Oceanic melting beneath ice shelves is the main driver of the current mass loss of the Antarctic ice sheet and is mostly parameterised in stand-alone ice-sheet modelling. Parameterisations are crude representations of reality, and their response to ocean warming has not been compared to 3-D ocean–ice-sheet coupled models. Here, we assess various melting parameterisations ranging from simple scalings with far-field thermal driving to emulators of box and plume models, using a new coupling framework combining the ocean model NEMO and the ice-sheet model Elmer/Ice. We define six idealised one-century scenarios for the far-field ocean ranging from cold to warm, and representative of potential futures for typical Antarctic ice shelves. The scenarios are used to constrain an idealised geometry of the Pine Island glacier representative of a relatively small cavity. Melt rates and sea-level contributions obtained with the parameterised stand-alone ice-sheet model are compared to the coupled model results. The plume parameterisations give good results for cold scenarios but fail and underestimate sea level contribution by tens of percent for warm(ing) scenarios, which may be improved by adapting its empirical scaling. The box parameterisation with five boxes compares fairly well to the coupled results for almost all scenarios, but further work is needed to grasp the correct number of boxes. For simple scalings, the comparison to the coupled framework shows that a quadratic as opposed to linear dependency on thermal forcing is required. In addition, the quadratic dependency is improved when melting depends on both local and non-local, i.e. averaged over the ice shelf, thermal forcing. The results of both the box and the two quadratic parameterisations fall within or close to the coupled model uncertainty. All parameterisations overestimate melting for thin ice shelves while underestimating melting in deep water near the grounding line. Further work is therefore needed to assess the validity of these melting parameteriations in more realistic set-ups.

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Section: Simple Functions Of Thermal Forcingmentioning

confidence: 99%

Assessment of sub-shelf melting parameterisations using the ocean–ice-sheet coupled model NEMO(v3.6)–Elmer/Ice(v8.3)

et al. 2019

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“…In the latter case, mass continuity is evolved at the ocean model's time step, thus ensuring that the freshwater (volume) flux translates conservatively into a corresponding change in geometry (vertical coupling). Furthermore, ice sheet retreat or advance (horizontal coupling) is achieved through maintenance of a thin or massless ocean layer below the (grounded) ice sheet, controlled by a porous flux (Goldberg et al, 2018;Jordan et al, 2018). Faithful representation of glacierfjord (Greenland) and ice shelf-ocean (Antarctica) interactions remains among the premier challenges in climate modeling in support of sea level science.…”

Section: Ice Shelves and Icebergsmentioning

confidence: 99%

Challenges and Prospects in Ocean Circulation Models

et al. 2019

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We revisit the challenges and prospects for ocean circulation models following Griffies et al. (2010). Over the past decade, ocean circulation models evolved through improved understanding, numerics, spatial discretization, grid configurations, parameterizations, data assimilation, environmental monitoring, and process-level observations and modeling. Important large scale applications over the last decade are simulations of the Southern Ocean, the Meridional Overturning Circulation and its variability, and regional sea level change. Submesoscale variability is now routinely resolved in process models and permitted in a few global models, and submesoscale effects are parameterized in most global models. The scales where nonhydrostatic effects become important are beginning to be resolved in regional and process models. Coupling to sea ice, ice shelves, and high-resolution atmospheric models has stimulated new ideas and driven improvements in numerics. Observations have provided insight into turbulence and mixing around the globe and its consequences are assessed through perturbed physics models. Relatedly, parameterizations of the mixing and overturning processes in boundary layers and the ocean interior have improved. New diagnostics being used for evaluating models Fox-Kemper et al. Ocean Circulation Models alongside present and novel observations are briefly referenced. The overall goal is summarizing new developments in ocean modeling, including: how new and existing observations can be used, what modeling challenges remain, and how simulations can be used to support observations.

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“…Concerns over the implications of rising sea levels call for the joint treatment of the coupled ocean-ice sheet system. Substantial progress is being made, both with asynchronous coupling between the MITgcm and the Ice Sheet System Model (ISSM, Seroussi et al, 2017) as well as with synchronous, property-conserving coupling between the MITgcm's ocean and ice stream/shelf model (Goldberg et al, 2018;Jordan et al, 2018). The availability of adjoint models of all of these components, along with at least annually resolved satellite observations at Antarctica's marine margins, offer the prospect of developing a tightly coupled, skillful estimation system.…”

Section: Coupled Ocean-ice Sheet Estimationmentioning

confidence: 99%

Putting It All Together: Adding Value to the Global Ocean and Climate Observing Systems With Complete Self-Consistent Ocean State and Parameter Estimates

Heimbach¹,

Fukumori²,

Hill³

et al. 2019

Front. Mar. Sci.

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Representing grounding line migration in synchronous coupling between a marine ice sheet model and a z-coordinate ocean model

Cited by 25 publications

References 62 publications

Assessment of sub-shelf melting parameterisations using the ocean–ice-sheet coupled model NEMO(v3.6)–Elmer/Ice(v8.3)

Assessment of sub-shelf melting parameterisations using the ocean–ice-sheet coupled model NEMO(v3.6)–Elmer/Ice(v8.3)

Challenges and Prospects in Ocean Circulation Models

Putting It All Together: Adding Value to the Global Ocean and Climate Observing Systems With Complete Self-Consistent Ocean State and Parameter Estimates

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