Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter

Gillet-Chaulet, Fabien

doi:10.5194/tc-14-811-2020

Cited by 24 publications

(26 citation statements)

References 95 publications

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“…New techniques have been and will need to be further explored to improve initialization methods using both observed surface elevation and ice velocity changes, allowing for improved understanding of underlying friction laws and rheological conditions of marine-terminating glaciers (Gillet-Chaulet and others, 2016; Gillet-Chaulet, 2020). Observations in regions with large changes can be used to discriminate different parameterizations.…”

Section: Discussionmentioning

confidence: 99%

“…Joughin and others (2009), Joughin and others (2019) and Gillet-Chaulet and others (2016) have shown that plastic laws are better suited for fast flowing areas in Pine Island Glacier in the Amundsen Sea Embayment, which in the light of this study makes a strong case for the increased sensitivity of grounding-line retreat and ice-sheet response relative to the commonly used sliding laws. Transient data assimilation (Goldberg and others, 2015; Gillet-Chaulet, 2020) that allow to capture observed rates of change should give better confidence in projections and enable reanalysis to better comprehend processes that drive past changes.…”

Section: Discussionmentioning

confidence: 99%

“…Journal of Glaciology 9 others, 2017) are based on seminal work by others (2000a, 2000b), but it is clear that more research in subglacial hydrology and basal mechanics of marine ice sheets is needed. New techniques have been and will need to be further explored to improve initialization methods using both observed surface elevation and ice velocity changes, allowing for improved understanding of underlying friction laws and rheological conditions of marine-terminating glaciers (Gillet-Chaulet Gillet-Chaulet, 2020). Observations in regions with large changes can be used to discriminate different parameterizations.…”

Section: Subglacial Hydrologymentioning

confidence: 99%

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Antarctic ice sheet response to sudden and sustained ice-shelf collapse (ABUMIP)

et al. 2020

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Antarctica's ice shelves modulate the grounded ice flow, and weakening of ice shelves due to climate forcing will decrease their ‘buttressing’ effect, causing a response in the grounded ice. While the processes governing ice-shelf weakening are complex, uncertainties in the response of the grounded ice sheet are also difficult to assess. The Antarctic BUttressing Model Intercomparison Project (ABUMIP) compares ice-sheet model responses to decrease in buttressing by investigating the ‘end-member’ scenario of total and sustained loss of ice shelves. Although unrealistic, this scenario enables gauging the sensitivity of an ensemble of 15 ice-sheet models to a total loss of buttressing, hence exhibiting the full potential of marine ice-sheet instability. All models predict that this scenario leads to multi-metre (1–12 m) sea-level rise over 500 years from present day. West Antarctic ice sheet collapse alone leads to a 1.91–5.08 m sea-level rise due to the marine ice-sheet instability. Mass loss rates are a strong function of the sliding/friction law, with plastic laws cause a further destabilization of the Aurora and Wilkes Subglacial Basins, East Antarctica. Improvements to marine ice-sheet models have greatly reduced variability between modelled ice-sheet responses to extreme ice-shelf loss, e.g. compared to the SeaRISE assessments.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Subglacial Hydrologymentioning

confidence: 99%

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Antarctic ice sheet response to sudden and sustained ice-shelf collapse (ABUMIP)

et al. 2020

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“…Assimilation methods, on the other hand, capture the present-day geometry, but projections often suffer from unrealistic drifts due to the model responding to inconsistencies in the input datasets. Timedependent data assimilation methods allow for more realistic transients, but to date they have been limited to regional studies or synthetic ice sheet setup (e.g., Goldberg et al, 2015;Gillet-Chaulet, 2020). Other methods include combinations of these techniques, as demonstrated in the initMIP Greenland and Antarctica efforts (Goelzer et al, 2018;.…”

Section: Overview Of the Projection Setup And Their Purposementioning

confidence: 99%

Experimental protocol for sea level projections from ISMIP6 stand-alone ice sheet models

et al. 2020

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Abstract. Projection of the contribution of ice sheets to sea level change as part of the Coupled Model Intercomparison Project Phase 6 (CMIP6) takes the form of simulations from coupled ice sheet–climate models and stand-alone ice sheet models, overseen by the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). This paper describes the experimental setup for process-based sea level change projections to be performed with stand-alone Greenland and Antarctic ice sheet models in the context of ISMIP6. The ISMIP6 protocol relies on a suite of polar atmospheric and oceanic CMIP-based forcing for ice sheet models, in order to explore the uncertainty in projected sea level change due to future emissions scenarios, CMIP models, ice sheet models, and parameterizations for ice–ocean interactions. We describe here the approach taken for defining the suite of ISMIP6 stand-alone ice sheet simulations, document the experimental framework and implementation, and present an overview of the ISMIP6 forcing to be used by participating ice sheet modeling groups.

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“…To validate the assimilation with independent observations, temperature and salinity profiles from the EN4 data set (EN4.2.1) of the UK Met Office (Good et al, 2013) are used. This collection of in situ data contains about 1000 to 2000 profiles per day at depths between the surface and 5000 m depth.…”

Section: Application Examplementioning

confidence: 99%

Efficient ensemble data assimilation for coupled models with the Parallel Data Assimilation Framework: example of AWI-CM (AWI-CM-PDAF 1.0)

Nerger

Tang

2020

Geosci. Model Dev.

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Abstract. Data assimilation integrates information from observational measurements with numerical models. When used with coupled models of Earth system compartments, e.g., the atmosphere and the ocean, consistent joint states can be estimated. A common approach for data assimilation is ensemble-based methods which utilize an ensemble of state realizations to estimate the state and its uncertainty. These methods are far more costly to compute than a single coupled model because of the required integration of the ensemble. However, with uncoupled models, the ensemble methods also have been shown to exhibit a particularly good scaling behavior. This study discusses an approach to augment a coupled model with data assimilation functionality provided by the Parallel Data Assimilation Framework (PDAF). Using only minimal changes in the codes of the different compartment models, a particularly efficient data assimilation system is generated that utilizes parallelization and in-memory data transfers between the models and the data assimilation functions and hence avoids most of the file reading and writing, as well as model restarts during the data assimilation process. This study explains the required modifications to the programs with the example of the coupled atmosphere–sea-ice–ocean model AWI-CM (AWI Climate Model). Using the case of the assimilation of oceanic observations shows that the data assimilation leads only to small overheads in computing time of about 15 % compared to the model without data assimilation and a very good parallel scalability. The model-agnostic structure of the assimilation software ensures a separation of concerns in which the development of data assimilation methods can be separated from the model application.

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Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter

Cited by 24 publications

References 95 publications

Antarctic ice sheet response to sudden and sustained ice-shelf collapse (ABUMIP)

Antarctic ice sheet response to sudden and sustained ice-shelf collapse (ABUMIP)

Experimental protocol for sea level projections from ISMIP6 stand-alone ice sheet models

Efficient ensemble data assimilation for coupled models with the Parallel Data Assimilation Framework: example of AWI-CM (AWI-CM-PDAF 1.0)

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