A two-dimensional glacier–fjord coupled model applied to estimate submarine melt rates and front position changes of Hansbreen, Svalbard

Andrés, Eva De; Otero, Jaime; Navarro, Francisco; Promińska, Agnieszka; Lapazaran, Javier; Walczowski, Waldemar

doi:10.1017/jog.2018.61

Cited by 18 publications

(62 citation statements)

References 61 publications

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“…According to De Andres et al. (2018), it may take up to a month for surface meltwater to penetrate and activate the englacial and subglacial drainage network. However, our results show that alternation between retreat and advance does not coincide with an increase in PDDs but with the rise of sea water temperature.…”

Section: Discussionmentioning

confidence: 99%

Factors Controlling Terminus Position of Hansbreen, a Tidewater Glacier in Svalbard

et al. 2021

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The mechanism of glacier recession and its climatic controls are complex processes that differ across the Arctic region. Here, we investigate factors influencing front variations of Hansbreen, a glacier terminated in Hornsund fjord (SW Svalbard). We apply remote sensing data to observe glacier front fluctuations between 1992 and 2015 and compare them to atmospheric and oceanographic data, sea water depth at the terminus and surface velocity. Rate of subglacial meltwater discharge approximated by the seasonal positive degree‐day index (PDD) together with sea thermal conditions appear to be the main factors responsible for the fluctuations of the front of Hansbreen, while water depth at the front plays a secondary role. Taking into account ocean and air thermal conditions, the studied period has been divided into warm, cold and moderate years. The glacier retreated considerably throughout a bedrock overdeepening in the very warm period 2012–2014. This recession coincided with a slower ice flow due to intense subglacial runoff and increased submarine melting. The long‐term retreat was interrupted by glacier advances in colder years, regardless of water depth at the front. The slower recession rate was the combined effect of decreased subglacial melting and increased glacier movement associated with lower subglacial runoff. Although the seasonal PDD is a good indicator of the front fluctuations, the duration of the retreat and advance periods are strongly correlated with the sea surface temperature. Expected climate warming and an increase of water temperature in the West Spitsbergen Current will stimulate further recession of Hansbreen in future.

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Section: Discussionmentioning

confidence: 99%

Factors Controlling Terminus Position of Hansbreen, a Tidewater Glacier in Svalbard

et al. 2021

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“…Over the last 2 decades, the rate of mass loss from the Greenland ice sheet (GrIS) has quadrupled (Rignot et al, 2011;Shepherd et al, 2012). Approximately 60 % of this ice loss is attributed to increased ice sheet surface melting, while the remaining 40 % is due to marine-terminating glacier acceleration and retreat (Jiskoot et al, 2012;Moon et al, 2012) that is thought to result from increased iceberg calving and submarine melting at the glacial fronts (Bamber et al, 2012;van den Broeke et al, 2009;Enderlin et al, 2014). Thus, understanding processes at the glaciers' fronts is key if we are to understand ongoing changes and generate future projections.…”

Section: Introductionmentioning

confidence: 99%

Surface emergence of glacial plumes determined by fjord stratification

et al. 2020

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Abstract. Meltwater and sediment-laden plumes at tidewater glaciers, resulting from the localized subglacial discharge of surface melt, influence submarine melting of the glacier and the delivery of nutrients to the fjord's surface waters. It is usually assumed that increased subglacial discharge will promote the surfacing of these plumes. Here, at a western Greenland tidewater glacier, we investigate the counterintuitive observation of a non-surfacing plume in July 2012 (a year of record surface melting) compared to the surfacing of the plume in July 2013 (an average melt year). We combine oceanographic observations, subglacial discharge estimates and an idealized plume model to explain the observed plumes' behavior and evaluate the relative impact of fjord stratification and subglacial discharge on plume dynamics. We find that increased fjord stratification prevented the plume from surfacing in 2012, show that the fjord was more stratified in 2012 due to increased freshwater content and speculate that this arose from an accumulation of ice sheet surface meltwater in the fjord in this record melt year. By developing theoretical scalings, we show that fjord stratification in general exerts a dominant control on plume vertical extent (and thus surface expression), so that studies using plume surface expression as a means of diagnosing variability in glacial processes should account for possible changes in stratification. We introduce the idea that, despite projections of increased surface melting over Greenland, the appearance of plumes at the fjord surface could in the future become less common if the increased freshwater acts to stratify fjords around the Greenland ice sheet. We discuss the implications of our findings for nutrient fluxes, trapping of atmospheric CO2 and the properties of water exported from Greenland's fjords.

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“…Although this is a widespread assumption in glacier-fjord studies (Mankoff et al, 2016;Slater et al, 2018;Stevens et al, 2016), it is a simplification because a number of hydrological processes will act to delay this meltwater, including storage of water in supra-and sub-glacial lakes, and the finite transit time of meltwater along the ice sheet surface and bed (Fountain and Walder, 1998). This delay is likely to be significantly longer, perhaps even weeks, at the beginning of the melt season when there is still a significant snowpack and the subglacial drainage system may be inefficient (De Andrés et al, 2018;Campbell et al, 2006;Cowton et al, 2013;Schild et al, 2016). As the melt season progresses, drainage becomes more efficient with subglacial transit velocities exceeding 1 m s -https://doi.org/10.5194/tc-2019-264 Preprint.…”

Section: Impact Of Fjord Stratification On Plume Dynamics In Saqqarlementioning

confidence: 99%

“…Through their vigorous turbulent nature, they enable the transfer of ocean heat to the ice, enhancing submarine melting of the glacial front (Kimura et al, 2014;Sciascia et al, 2013;Slater et al, 2015Slater et al, , 2018Xu et al, 2013). In addition, they likely affect calving rates by incising undercut notches into the terminus, altering the stress distribution of ice near the terminus (De Andrés et al, 2018;How et al, 2019;Luckman et al, 2015;O'Leary and Christoffersen, 2013;Schild et al, 2018;Vallot et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Surface emergence of glacial plumes determined by fjord stratification

Andrés¹,

Slater²,

Straneo³

et al. 2020

Preprint

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Abstract. Meltwater and sediment-laden plumes at tidewater glaciers, resulting from the localized subglacial discharge of surface melt, influence submarine melting of the glacier and the delivery of nutrients to the fjord's surface waters. It is usually assumed that increased subglacial discharge will promote the surfacing of these plumes. Here, at a west Greenland tidewater glacier, we investigate the counterintuitive observation of a non-surfacing plume in July 2012 (a year of record surface melting) compared to the surfacing of the plume in July 2013 (an average melt year). We combine oceanographic observations, subglacial discharge estimates and an idealized plume model to explain the observed plumes’ behavior and evaluate the relative impact of fjord stratification and subglacial discharge on plume dynamics. We find that increased fjord stratification prevented the plume from surfacing in 2012, show that the fjord was more stratified in 2012 due to increased freshwater content, and speculate that this arose from an accumulation of ice sheet surface meltwater in the fjord in this record melt year. By developing theoretical scalings, we show in general that fjord stratification exerts a dominant control on plume vertical extent (and thus surface expression), so that studies using plume surface expression as a means of diagnosing variability in glacial processes should account for possible changes in stratification. We introduce the idea that despite projections of increased surface melting over Greenland, the appearance of plumes at the fjord surface could in the future become less common if the increased freshwater acts to stratify fjords around the ice sheet. We discuss the implications of our findings for nutrient fluxes, trapping of atmospheric CO2 and the properties of water exported from Greenland’s fjords.

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A two-dimensional glacier–fjord coupled model applied to estimate submarine melt rates and front position changes of Hansbreen, Svalbard

Cited by 18 publications

References 61 publications

Factors Controlling Terminus Position of Hansbreen, a Tidewater Glacier in Svalbard

Factors Controlling Terminus Position of Hansbreen, a Tidewater Glacier in Svalbard

Surface emergence of glacial plumes determined by fjord stratification

Surface emergence of glacial plumes determined by fjord stratification

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