Oceanic heat delivery via Kangerdlugssuaq Fjord to the south‐east Greenland ice sheet

Inall, Mark; Murray, Tavi; Cottier, Finlo; Scharrer, K.; Boyd, T.; Heywood, Karen J.; Bevan, Suzanne

doi:10.1002/2013jc009295

Cited by 84 publications

(165 citation statements)

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“…These studies have provided novel insights into the water masses, stratification, and the spread of glacially modified water (often subsurface) (e.g. Johnson et al, 2011;Straneo et al, 2011;Inall et al, 2014). However,…”

Section: Unknown Dynamics In Glacial Fjordsmentioning

confidence: 99%

“…A similar water mass structure is found in Kangerdlugssuaq, with additional dense Atlantic water originating in the Nordic Seas . In both Sermilik and Kangerdlugssuq fjords, the shallowest sills (at 530 and 550 m, respectively) are well below the AW/PW interface (Schjøth et al, 2012;Sutherland et al, 2013;Inall et al, 2014), allowing for relatively unimpeded exchange between the fjord and shelf (bathymetry shown in Fig. 2-1a & b).…”

Section: Settingmentioning

confidence: 99%

“…In some cases, the raw snapshots of velocity and water properties are used to calculate cross-section transport (Xu et al, 2013;Motyka et al, 2003Motyka et al, , 2013Rignot et al, 2010). In others, geostrophic velocities are calculated from water properties (Johnson et al, 2011;Inall et al, 2014) or a high frequency mode is removed from the velocity field (Sutherland and Straneo, 2012).…”

Section: Measuring a Mean Velocity Profilementioning

confidence: 99%

“…Limited velocity data indicates that shelf variability may play an important role in driving fjord flows (Rignot et al, 2010;Straneo et al, 2010), though conclusive evidence is absent. Furthermore, most observational studies rely on brief, summer surveys (Holland et al, 2008a;Rignot et al, 2010;Christoffersen et al, 2011;Straneo et al, 2011;Johnson et al, 2011;Xu et al, 2013;Inall et al, 2014) that offer limited insight into drivers of summer variability and no information about non-summer months.…”

Section: Introductionmentioning

confidence: 99%

“…A growing number of studies attempt to infer submarine melt rates from measurements of ocean heat transport in the fjords where outlet glaciers terminate (Motyka et al, 2003;Johnson et al, 2011;Sutherland and Straneo, 2012;Rignot et al, 2010;Christoffersen et al, 2011;Motyka et al, 2013;Xu et al, 2013;Inall et al, 2014;Mortensen et al, 2014). Water properties and velocity, usually measured over a brief period, are used to estimate ocean heat transport through a fjord cross-section.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of Greenland�s glacial fjords

Jackson¹

2016

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Glacial fjords form conduits between glaciers of the Greenland Ice Sheet and the North Atlantic. They are the gateways for importing oceanic heat to melt ice and for exporting meltwater into the ocean. Submarine melting in fjords has been implicated as a driver of recent glacier acceleration; however, there are no direct measurements of this melting, and little is known about the fjord processes that modulate melt rates. Combining observations, theory, and modeling, this thesis investigates the circulation, heat transport, and meltwater export in glacial fjords.While most recent studies focus on glacial buoyancy forcing, there are other drivers -e.g. tides, local wind, shelf variability -that can be important for fjord circulation. Using moored records from two major Greenlandic fjords, shelf forcing (from shelf density fluctuations) is found to dominate the fjord circulation, driving rapid exchange with the shelf and large heat content variability near the glacier. Contrary to the conventional paradigm, these flows mask any glacier-driven circulation in the non-summer months. During the summer, when shelf forcing is reduced and freshwater forcing peaks, a mean exchange flow transports warm Atlantic-origin water towards the glacier and exports glacial meltwater.Many recent studies have inferred submarine melt rates from oceanic heat transport, but the fjord budgets that underlie this method have been overlooked. Building on estuarine studies of salt fluxes, this thesis presents a new framework for assessing glacial fjord budgets and revised equations for inferring meltwater fluxes. Two different seasonal regimes are found in the heat/salt budgets for Sermilik Fjord, and the results provide the first time-series of submarine meltwater and subglacial discharge fluxes into a glacial fjord.Finally, building on the observations, ROMS numerical simulations and two analytical models are used to investigate the dynamics of shelf-driven flows and their importance relative to local wind forcing across the parameter space of Greenland's fjords. The fjord response is found to vary primarily with the width relative to the deformation radius and the fjord adjustment timescale relative to the forcing timescale. Understanding these modes of circulation is a step towards accurate modeling of ocean-glacier interactions.

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Section: Unknown Dynamics In Glacial Fjordsmentioning

confidence: 99%

Section: Settingmentioning

confidence: 99%

Section: Measuring a Mean Velocity Profilementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamics of Greenland�s glacial fjords

Jackson¹

2016

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Characteristics and dynamics of two major Greenland glacial fjords

2014

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The circulation regimes of two major outlet glacial fjords in southeastern Greenland, Sermilik Fjord (SF) and Kangerdlugssuaq Fjord (KF), are investigated using data collected in summer 2009. The two fjords show similar flow patterns, with a time-dependent, vertically sheared flow structure dominating over the background estuarine flow driven by buoyancy input. We show that this time-dependent flow is consistent with circulation induced by density interface fluctuations at the fjord mouth, often referred to as intermediary circulation. One difference between the fjords is that the hydrographic and velocity structure below a surface modified layer is found to be three layer in KF in summer, compared to two layer in SF. Outside each fjord, large-scale geostrophic currents dictate the stratification at the mouth, although the way in which these large-scale flows impinge on each fjord is distinct. Combining the observations with estimates from existing theories, we find the magnitudes of the estuarine (Q e ) and intermediary (Q i ) circulation and show that Q i >> Q e , although along-fjord winds can also be significant. We expect that the critical parameter determining Q i /Q e is the sill depth compared to the fjord depth, with shallower sills corresponding to weaker intermediary circulation. Finally, we discuss the implications of strong intermediary circulation on calculating heat transport to the glacier face and its potential feedbacks on the background circulation in these highly stratified estuaries.

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Seasonal variability of the warm Atlantic water layer in the vicinity of the Greenland shelf break

Grist

Josey

Boehme

et al. 2014

Geophysical Research Letters

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The warmest water reaching the east and west coast of Greenland is found between 200 and 600 m. While important for melting Greenland's outlet glaciers, limited winter observations of this layer prohibit determination of its seasonality. To address this, temperature data from Argo profiling floats, a range of sources within the World Ocean Database, and unprecedented coverage from marine-mammal borne sensors have been analyzed for the period 2002-2011. A significant seasonal range in temperature (~1-2°C) is found in the warm layer, in contrast to most of the surrounding ocean. The phase of the seasonal cycle exhibits considerable spatial variability, with the warmest water found near the eastern and southwestern shelf break toward the end of the calendar year. High-resolution ocean model trajectory analysis suggests the timing of the arrival of the year's warmest water is a function of advection time from the subduction site in the Irminger Basin.

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Oceanic heat delivery via Kangerdlugssuaq Fjord to the south‐east Greenland ice sheet

Cited by 84 publications

References 45 publications

Dynamics of Greenland�s glacial fjords

Dynamics of Greenland�s glacial fjords

Characteristics and dynamics of two major Greenland glacial fjords

Seasonal variability of the warm Atlantic water layer in the vicinity of the Greenland shelf break

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