Jag har jobbat på några kurser (båda på BSc och MSc nivå), till exempel:

GE7092 Glaciologi

GE7053 Paleoglaciologi

GE4030 Geographic Information Systems (GIS)

GE5033 Geomorfologiska processer, naturkatastrofer, och riskanalys

Mina forskningsintressen ligger inom områdena glaciologi, oceanografi, klimatvetenskap och arktiska/polära miljöer. Jag har ett särskilt intresse för glaciärer som slutar i fjordar/hav och de processer som kalvning och undervattenssmälta (tillsammans: frontal ablation) som sker vid detta gränssnitt.

Jag använder fältdata, satellit data och numerisk modellering (i Elmer/Ice och ISSM) för att undersöka kontrollerna av frontal ablation vid olika glaciärer och hur processer vid kalvningsfronten påverkar dynamiken i hela glaciären.

För närvarande är min forskning vid institutionen för geologiska vetenskaper fokuserad på norra Grönland och hur glaciärerna i denna sektor sannolikt kommer att bete sig fram till 2300.

I urval från Stockholms universitets publikationsdatabas

• Modelled frontal ablation and velocities at Kronebreen, Svalbard, are sensitive to the choice of submarine melt rate scenario

  2023. Felicity Alice Holmes, Eef van Dongen, Nina Kirchner. Journal of Glaciology

  Artikel

  Both submarine melt and calving are important for the overall mass balance of marine-terminating glaciers, but uncertainty is rife with regards to the magnitude of the processes. Modelling allows for these processes to be investigated without the need to visit inaccessible ice marginal zones. This study looks at the impact of different submarine melt and sea-ice back pressure scenarios on modelled calving activity and dynamics at Kronebreen, Svalbard, by running separate summer and winter simulations with various submarine melt parameterisations and sea-ice characteristics. It is found that submarine melt is an important driver of seasonal variation in modelled glacier dynamics and calving activity, with the choice of sliding law also exerting a significant influence on results.

  Läs mer om Modelled frontal ablation and velocities at Kronebreen, Svalbard, are sensitive to the choice of submarine melt rate scenario

• Impact of tides on calving patterns at Kronebreen, Svalbard – insights from three-dimensional ice dynamical modelling

  2023. Felicity A. Holmes (et al.). The Cryosphere 17 (5), 1853-1872

  Artikel

  Understanding calving processes and their controls is of importance for reducing uncertainty in sea level rise estimates. The impact of tidal fluctuations and frontal melt on calving patterns has been researched through both modelling and observational studies but remains uncertain and may vary from glacier to glacier. In this study, we isolate various different impacts of tidal fluctuations on a glacier terminus to understand their influence on the timing of calving events in a model of Kronebreen, Svalbard, for the duration of 1 month. In addition, we impose a simplified frontal melt parameterisation onto the calving front in order to allow for an undercut to develop over the course of the simulations. We find that calving events show a tidal signal when there is a small or no undercut, but, after a critical point, undercut-driven calving becomes dominant and drowns out the tidal signal. However, the relationship is complex, and large calving events show a tidal signal even with a large modelled undercut. The modelled undercut sizes are then compared to observational profiles, showing that undercuts of up to ca. 25 m are plausible but with a more complex geometry being evident in observations than that captured in the model. These findings highlight the complex interactions occurring at the calving front of Kronebreen and suggest further observational data and modelling work is needed to fully understand the hierarchy of controls on calving.

  Läs mer om Impact of tides on calving patterns at Kronebreen, Svalbard – insights from three-dimensional ice dynamical modelling

• Glacier-Ocean Interactions in the Arctic: Contemporary calving and frontal melt from field observations, remote sensing, and numerical modelling

  2022. Felicity Alice Holmes.

  Avhandling (Dok)

  Globally, glaciers are losing mass as a result of the changing climate, with this mass loss having a considerable societal impact through rising sea levels. Glaciers which terminate in the oceans are particularly vulnerable to changing external conditions as a result of high sensitivity at their marine margins. Both changing meteorological patterns as well as changing ocean heat content and transport have been previously identified as potential drivers for contemporary rapid glacier retreat and acceleration. However, uncertainties remain and provide motivation for studies which improve our process understanding. Here, we use a combination of field data, remotely sensed data, and targeted numerical modelling experiments to investigate marine terminating glacier response to external changes. This is done in order to address uncertainties around mass loss at the inaccessible glacier-ocean interface. In particular, focus is paid to the processes of submarine melt and calving, together referred to as frontal ablation. Submarine melt is the melting of glacier termini by warm ocean waters below the waterline, whilst calving is the breaking off of icebergs from glacier termini. The two processes are interlinked, with submarine melting undercutting the glacier terminus and contributing to calving, whilst calving events can expose larger areas of the glacier margin to submarine melt. To look for relationships between frontal ablation and external forcings, four glacier-fjord systems were studied to varying extents; two grounded glaciers in Svalbard (Kronebreen and Tunabreen) and two glaciers with floating ice tongues in Greenland (Ryder glacier and Petermann glacier). Both submarine melt and calving were examined at various different scales, both temporally and spatially. Specifically, analysis was carried out from the scale of individual calving events up to decadal long time series of glacier margin change. Much of the data used focused on specific glaciological variables such as satellite-derived velocities, margin positions, model simulations, and time-lapse photography of calving events. However, as glaciers and their adjacent fjord or ocean environments impact on each other, data such as water temperatures were also collected from glacier proximal fjord environments. The results from both the observational data and model experiments suggest that ocean temperatures are of great importance for the frontal ablation of glaciers in the Arctic, but that the relationship is complex. Heterogeneous glacier response to external forcings highlights how site specific factors such as bathymetry and fjord geometry can add an additional layer of complexity and make it challenging to scale up results from one glacier to an entire region. However, there are some strong indications that it is the presence of warm air temperatures in conjunction with warm ocean temperatures that is most important for driving frontal ablation - highlighting the need to situate glacier behaviour within a wider environmental context.

  Läs mer om Glacier-Ocean Interactions in the Arctic

• Supraglacial lake expansion, intensified lake drainage frequency, and first observation of coupled lake drainage, during 1985–2020 at Ryder Glacier, Northern Greenland

  2022. Jacqueline Otto, Felicity A. Holmes, Nina Kirchner. Frontiers in Earth Science 10

  Artikel

  Along the Greenland Ice Sheet margin, supraglacial lakes store and redistribute ice sheet surface run off, and comprise an important potential hydrological link between the ice surface and the base, with ramifications for subglacial drainage systems and ice flow. As a consequence of increasing global mean surface air temperatures, these lakes have been predicted to expand further inland and to affect larger areas of the ice sheet. However, as contemporary dynamics of such supraglacial lake expansion are not well studied, any assessment of their future implications remains afflicted with uncertainty. Here, recent changes in supraglacial lake distribution and expansion, and in their drainage behavior and frequency, are presented for Ryder Glacier, Northern Greenland, as concluded from a remote sensing based analysis. The 35-year time span covered in the analysis allows for the detection of trends in lake processes and ice velocity, which otherwise were found to exhibit large inter-annual variability. It also reveals the first occurrence of a coupled lake drainage event in 2002. By linking supraglacial lake expansion, drainage modes, and drainage frequency to the efficiency of the subglacial drainage system and ice flow on seasonal and decadal timescales, a contribution is made to better understand the complexity of coupled glacio-hydrological processes, and to help reduce uncertainties in predictions of future mass loss from the Greenland Ice Sheet.

  Läs mer om Supraglacial lake expansion, intensified lake drainage frequency, and first observation of coupled lake drainage, during 1985–2020 at Ryder Glacier, Northern Greenland

• Modelled dynamic retreat of Kangerlussuaq Glacier, East Greenland, strongly influenced by the consecutive absence of an ice mélange in Kangerlussuaq Fjord

  2022. Jamie Barnett, Felicity A. Holmes, Nina Kirchner. Journal of Glaciology

  Artikel

  Mass loss at the Greenland Ice Sheet is influenced by atmospheric processes controlling its surface mass balance, and by submarine melt and calving where glaciers terminate in fjords. There, an ice mélange - a composite matrix of calved ice bergs and sea ice - may provide a buttressing force on a glacier terminus and control terminus dynamics. Kangerlussuaq Glacier is a major outlet of the Greenland Ice Sheet, for which recent major retreat events in 2004/2005 and 2016-2018 coincided with the absence of an ice mélange in Kangerlussuaq Fjord. To better understand the response of Kangerlussuaq Glacier to climatic and oceanic drivers, a 2D flowline model is employed. Results indicate that an ice mélange buttressing force exerts a major control on calving frequency and rapid retreat. When an ice mélange forms in Kangerlussuaq Fjord, it provides stabilising forces and conditions favourable for winter terminus re-advance. When it fails to form during consecutive years, model results indicate that Kangerlussuaq Glacier is primed to retreat into the large overdeepenings in Kangerlussuaq Fjord, and to terminus positions more than 30 km farther inland, implying that excessive mass loss from Kangerlussuaq Glacier by the year 2065 cannot be excluded.

  Läs mer om Modelled dynamic retreat of Kangerlussuaq Glacier, East Greenland, strongly influenced by the consecutive absence of an ice mélange in Kangerlussuaq Fjord

• Calving at Ryder Glacier, Northern Greenland

  2021. Felicity A. Holmes (et al.). Journal of Geophysical Research - Earth Surface 126 (4)

  Artikel

  Recent evidence has shown increasing mass loss from the Greenland ice sheet, with a general trend of accelerated mass losses extending northwards. However, different glaciers have been shown to respond differently to similar external forcings, constituting a problem for extrapolating and upscaling data. Specifically, whilst some outlet glaciers have accelerated, thinned, and retreated in response to atmospheric and oceanic warming, the behavior of other marine terminating glaciers appears to be less sensitive to climate forcing. Ryder glacier, for which only a few studies have been conducted, is located in North Greenland and terminates with a floating ice tongue in Sherard Osborn Fjord. The persistence or disintegration of floating ice tongues has impacts on glacier dynamics and stability, with ramifications beyond, including sea level rise. This study focuses on understanding the controls on calving and frontal ablation of the Ryder glacier through the use of time-lapse imagery and satellite data. The results suggest that Ryder glacier has behaved independently of climate forcing during recent decades, with fjord geometry exerting a first order control on its calving.

  Läs mer om Calving at Ryder Glacier, Northern Greenland

• Ryder Glacier in northwest Greenland is shielded from warm Atlantic water by a bathymetric sill

  2020. Martin Jakobsson (et al.). Communications Earth & Environment 1 (1)

  Artikel

  The processes controlling advance and retreat of outlet glaciers in fjords draining the Greenland Ice Sheet remain poorly known, undermining assessments of their dynamics and associated sea-level rise in a warming climate. Mass loss of the Greenland Ice Sheet has increased six-fold over the last four decades, with discharge and melt from outlet glaciers comprising key components of this loss. Here we acquired oceanographic data and multibeam bathymetry in the previously uncharted Sherard Osborn Fjord in northwest Greenland where Ryder Glacier drains into the Arctic Ocean. Our data show that warmer subsurface water of Atlantic origin enters the fjord, but Ryder Glacier's floating tongue at its present location is partly protected from the inflow by a bathymetric sill located in the innermost fjord. This reduces under-ice melting of the glacier, providing insight into Ryder Glacier's dynamics and its vulnerability to inflow of Atlantic warmer water. A bathymetric sill in Sherard Osborn Fjord, northwest Greenland shields Ryder Glacier from melting by warm Atlantic water found at the bottom of the fjord, according to high-resolution bathymetric mapping and oceanographic data.

  Läs mer om Ryder Glacier in northwest Greenland is shielded from warm Atlantic water by a bathymetric sill

• Relating ocean temperatures to frontal ablation rates at Svalbard tidewater glaciers: Insights from glacier proximal datasets

  2019. Felicity A. Holmes (et al.). Scientific Reports 9

  Artikel

  Fjord-terminating glaciers in Svalbard lose mass through submarine melt and calving (collectively: frontal ablation), and surface melt. With the recently observed Atlantification of water masses in the Barents Sea, warmer waters enter these fjords and may reach glacier fronts, where their role in accelerating frontal ablation remains insufficiently understood. Here, the impact of ocean temperatures on frontal ablation at two glaciers is assessed using time series of water temperature at depth, analysed alongside meteorological and glaciological variables. Ocean temperatures at depth are harvested at distances of 1 km from the calving fronts of the glaciers Kronebreen and Tunabreen, western Svalbard, from 2016 to 2017. We find ocean temperature at depth to control c. 50% of frontal ablation, making it the most important factor. However, its absolute importance is considerably less than found by a 2013-2014 study, where temperatures were sampled much further away from the glaciers. In light of evidence that accelerating levels of global mass loss from marine terminating glaciers are being driven by frontal ablation, our findings illustrate the importance of sampling calving front proximal water masses.

  Läs mer om Relating ocean temperatures to frontal ablation rates at Svalbard tidewater glaciers

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