Atlantic water variability on the SE Greenland continental shelf and its relationship to SST and bathymetry

Sutherland, David A.; Straneo, Fiammetta; Stenson, Garry B.; Davidson, Fraser; Hammill, Mike O.; Rosing‐Asvid, Aqqalu

doi:10.1029/2012jc008354

Cited by 65 publications

(117 citation statements)

References 39 publications

Supporting

Mentioning

105

Contrasting

Order By: Relevance

“…The west Greenland current advects deep (> 400 m), warm (> 3 • C) and saline (> 34.8 PSU -practical salinity units) Atlantic water around the south coast of Greenland, transferring large fluxes of thermal energy of a subtropical origin into this sensitive polar environment Holland et al, 2008;Kjaer et al, 2012;Mortensen et al, 2011;Ribergaard, 2007;Sutherland et al, 2013). The frontal dynamics of tidewater outlet glaciers draining the Greenland Ice Sheet (GrIS) can be profoundly influenced by Atlantic water (AW), which has the potential to directly access their…”

Section: Introductionmentioning

confidence: 99%

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

et al. 2014

View full text Add to dashboard Cite

Abstract. Warm, subtropical-originating Atlantic water (AW) has been identified as a primary driver of mass loss across the marine sectors of the Greenland Ice Sheet (GrIS), yet the specific processes by which this water mass interacts with and erodes the calving front of tidewater glaciers is frequently modelled and much speculated upon but remains largely unobserved. We present a suite of fjord salinity, temperature, turbidity versus depth casts along with glacial runoff estimation from Rink and Store glaciers, two major marine outlets draining the western sector of the GrIS during 2009 and 2010. We characterise the main water bodies present and interpret their interaction with their respective calving fronts. We identify two distinct processes of iceocean interaction which have distinct spatial and temporal footprints: (1) homogenous free convective melting which occurs across the calving front where AW is in direct contact with the ice mass, and (2) localised upwelling-driven melt by turbulent subglacial runoff mixing with fjord water which occurs at distinct injection points across the calving front. Throughout the study, AW at 2.8 ± 0.2 • C was consistently observed in contact with both glaciers below 450 m depth, yielding homogenous, free convective submarine melting up to ∼ 200 m depth. Above this bottom layer, multiple interactions are identified, primarily controlled by the rate of subglacial fresh-water discharge which results in localised and discrete upwelling plumes. In the record melt year of 2010, the Store Glacier calving face was dominated by these runoff-driven plumes which led to a highly crenulated frontal geometry characterised by large embayments at the subglacial portals separated by headlands which are dominated by calving. Rink Glacier, which is significantly deeper than Store has a larger proportion of its submerged calving face exposed to AW, which results in a uniform, relatively flat overall frontal geometry.

show abstract

Section: Introductionmentioning

confidence: 99%

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

et al. 2014

View full text Add to dashboard Cite

show abstract

“…There are, however, some notable exceptions. The average melt rate estimate for Koge Bugt is nearly double the average melt rate for icebergs calved from Helheim Glacier despite similar water temperatures near the fjord mouths (Sutherland et al, 2013). Although our Koge Bugt dataset includes only six icebergs across two observation periods, we observe melt rates of >0.6 m/d during both observation periods, increasing our confidence that the difference in average melt rates reflects variations in typical melt conditions at the two study sites and is 20 not due to observational uncertainties or anomalous melt conditions.…”

Section: Regional Patternsmentioning

confidence: 88%

Greenland Iceberg Melt Variability from High-Resolution Satellite Observations

Enderlin¹,

Carrigan²,

Kochtitzky³

et al. 2017

Preprint

View full text Add to dashboard Cite

Abstract. Iceberg discharge from the Greenland Ice Sheet accounts for up to half of the freshwater flux to surrounding fjords and ocean basins, yet the spatial distribution of iceberg meltwater fluxes is poorly understood. One of the primary limitations for mapping iceberg meltwater fluxes, and changes over time, is the dearth of iceberg submarine melt rate estimates. Here we use a remote sensing approach to estimate submarine melt rates during 2011-2016 for 637 icebergs discharged from seven large marine-terminating glaciers fringing the Greenland Ice Sheet. We find that spatial variations in iceberg melt rates 15 generally follow expected patterns based on hydrographic observations, including a general decrease in melt rate with latitude and an increase in melt rate with iceberg draft. We do not resolve coherent temporal variations in iceberg melt rates across all study sites, though we attribute a four-fold increase in iceberg melt rates from March to April 2011 near Jakobshavn Isbrae's terminus to rapid fjord circulation changes induced by the seasonal onset of iceberg calving. Overall, our results suggest that remotely-sensed iceberg melt rates can be used to characterize spatial and temporal variations in oceanic 20 forcing near marine-terminating glaciers, including regions largely inaccessible for in situ study.

show abstract

“…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%

“…The RACMO runoff time-series provides context for the seasonality of freshwater fluxes and a point of comparison for our inferred runoff flux. Lastly, we use bathymetry data from Sutherland et al (2013) and Schjøth et al (2012) for Sermilik Fjord and the adjacent shelf region ( Fig. 3-2).…”

Section: Background On Sermilik Fjord Regionmentioning

confidence: 99%

Dynamics of Greenland�s glacial fjords

Jackson¹

2016

View full text Add to dashboard Cite

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.

show abstract

Atlantic water variability on the SE Greenland continental shelf and its relationship to SST and bathymetry

Cited by 65 publications

References 39 publications

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

Greenland Iceberg Melt Variability from High-Resolution Satellite Observations

Dynamics of Greenland�s glacial fjords

Contact Info

Product

Resources

About