Prof. Elisa Mantelli

Research

Prof. Mantelli leads the Ice Sheet Dynamics research group. Our research spans a variety of topics in glaciology, including the dynamics of fast ice flow, subglacial and surface hydrology, basal sliding, and ice-ocean interactions. The common thread among these topics is that the processes involved have the potential to drive the dynamics and evolution of a whole ice sheet through changes in ice flow. Understanding how and when this may happen is the ultimate goal of our research. To achieve this, we build off a diverse skill set that is grounded in fluid mechanics and applied mathematics, which we combine with observation-driven work.

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Ice stream dynamics

Ice streams are river-like corridors of fast flowing ice that account for the vast majority of ice discharge to the ocean in continental ice sheets. Their most outstanding feature is that they can appear spontaneously within a slowly moving ice sheet, self-organize in evenly spaced patterns, and switch on and off over time. Yet, a full explanation of ice stream formation and evolution is one of the longest standing open problems in glaciology. This knowledge gap has precluded fundamental investigations on the role of ice streams in driving ice sheet change, and also casts doubt on the ability of state-of-the-art ice sheet simulation codes to project future sea levels. Recent research from our group identified novel feedbacks related to the onset of basal sliding which could be the missing ingredient needed to fully explain observed ice stream dynamic behaviors. Drawing on a unique combination of novel glaciological observations, first-principle theoretical work, and ice-sheet-wide numerical simulations, our ERC Starting Grant Project PHAST: A Physics based study of Ice Stream Dynamics builds on this insight to unravel the complex interplay between internal ice sheet dynamics and climate over decades to millennia.

Running projects

• PHAST - A physics-based study of ice stream dynamics (EU, ERC Starting Grant, since 2023)

Schoof Christian and Mantelli Elisa 2021The role of sliding in ice stream formation, Proc. R. Soc. A.47720200870http://doi.org/10.1098/rspa.2020.0870

E. Mantelli, M.B. Bertagni, & L. Ridolfi, Stochastic ice stream dynamics, Proc. Natl. Acad. Sci. U.S.A. 113 (32) E4594-E4600, https://doi.org/10.1073/pnas.1600362113 (2016).

The physics of basal sliding

Another research focus is sliding at the interface between ice and the substrate, a key phenomenon driving glacier and ice sheet dynamics. We explore the physics of sliding at the ice-bed interface through mathematical modeling and direct observations. A current topic is subtemperate sliding, where ice can slide even when temperature is below the pressure melting point. Our research in this area seeks to understand the role of subtemperate sliding in the thermo-mechanics of sliding initiation at frozen/thawed basal thermal transitions and its role in the onset of ice streams. The angle of our current work is predominantly observational: we are working at one of a handful of alpine glaciers experiencing a frozen-thawed basal transition to characterize how sliding first starts through direct access of the bed. The measurements we will undertake, combined with first-principle modelling work, will help us constrain the physics of sliding initiation and how these should be described mathematically in ice sheet simulation codes used to predict ice sheet and sea level change.

Running projects:

• PHAST - A physics-based study of ice stream dynamics (EU, ERC Starting Grant, since 2023)

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The Grenzgletscher natural laboratory

We run an analogue field experiment at the Grenzgletscher (Switzerland), in the Monte Rosa Massif. This glacier is unique in that it experiences a thermal regime akin to that of much larger ice streams found in Antarctica and Greenland. Frozen at the bed at the head of the catchment (colle Gnifetti, 4455 m), the cold ice accumulated there is advected all the way down to the lower ablation area at less than 2500 m, where a basal layer of temperate (i.e., at the melting point) ice forms as a result of internal heat dissipation. This peculiar polythermal structure makes the glacier an ideal analogue site to investigate the physics of sliding at basal thermal transitions as part of the ERC project PHAST. Our field program has also served to gather colleagues from other branches of glaciology around the same field site, which is now serving as a natural laboratory to test geophysical techniques and investigate a variety of topics in the field of alpine glaciology.

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Constraining ice flow models with geophysical observations

Another research focus in our group is the integration of geophysical observations into ice flow models. Here our goal is to advance the understanding of ice sheet physics by constraining ice flow model with observations. A main target here is basal processes, which are notoriously difficult to observe directly. Some of our work in this area concerns using constraints from radar sounding (especially basal reflectivity and englacial attenuation) to get at basal thermal conditions, as well as the geometry of englacial layers as a proxy for basal friction. We are also broadly interested in sub-ice shelf melting, as well as in sub-glacial hydrology, especially in alpine settings.

Dawson, E. J., Schroeder, D. M., Chu, W., Mantelli, E., & Seroussi, H. (2024). Heterogeneous basal thermal conditions underpinning the Adélie-George V Coast, East Antarctica. Geophysical Research Letters, 51, e2023GL105450. https://doi.org/10.1029/2023GL105450

Castelletti D, Schroeder DM, Mantelli E, Hilger A. Layer optimized SAR processing and slope estimation in radar sounder data. Journal of Glaciology. 2019;65(254):983-988. doi:10.1017/jog.2019.72

Goldberg ML, Schroeder DM, Castelletti D, Mantelli E, Ross N, Siegert MJ. Automated detection and characterization of Antarctic basal units using radar sounding data: demonstration in Institute Ice Stream, West Antarctica. Annals of Glaciology. 2020;61(81):242-248. doi:10.1017/aog.2020.27

Theoretical aspects of glacier and ice sheet flow

With our foundation in fluid dynamics and applied mathematics, we also work on developing mathematical models of key processes relevant to ice sheet and glacier flow. In general we are interested in questions concerning physical processes that remain difficult to represent in numerical ice sheet/ice flow models, specifically on coming up with rigorous, realistic, and yet tractable mathematical representations of these processes that can be implemented in numerical models. A recent focus has been on ice fabrics, and its role in controlling ice viscosity, as well on how fabric development should be modeled. Other areas of interest at the moment include ice sheet thermo-dynamics, ice stream onset regions, and parameterizations of ice shelf melt rate.

Mantelli E, Haseloff M, Schoof C. 2019 Ice sheet flow with thermally activated sliding. Part 1: the role of advection. Proc. R. Soc. A 475: 20190410. http://dx.doi.org/10.1098/rspa.2019.0410

Mantelli E, Schoof C. 2019 Ice sheet flow with thermally activated sliding. Part 2: the stability of subtemperate regions. Proc. R. Soc. A 475: 20190411. http://dx.doi.org/10.1098/rspa.2019.0411

Hank, K., Tarasov, L., and Mantelli, E.: Modeling sensitivities of thermally and hydraulically driven ice stream surge cycling, Geosci. Model Dev., 16, 5627–5652, https://doi.org/10.5194/gmd-16-5627-2023, 2023.
Richards, D. H., Mantelli, E., Pegler, S. S., and Piazolo, S.: A comparative study of fabric evolution models and anisotropic rheologies, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2024-3067, 2024.

Publications