Abstract
Abstract. The oceanic heat available in Greenland’s troughs is dependent on the geographic location of the trough, the water origin, and how the water is impacted by local processes along the pathway to the trough. This study investigates the spatial pattern and quantity of the warm water (with a temperature greater −1.5 ∘C) brought to the shelf and into the troughs abutting the Greenland Ice Sheet (GrIS). An increase in ocean heat in these troughs may drive a retreat of the GrIS. Warm water that is exchanged from the trough into the fjord may influence the melt on the marine-terminating glaciers. Several regional ocean model experiments were used to study regional differences in heat transport through troughs. Results showed that warm water extends north into Baffin Bay, reaching as far north as the Melville Bay troughs. Melville Bay troughs experienced warming following 2009. From 2004 to 2006, model experiments captured an increase in onshore heat flux in the Disko Bay trough, coinciding with the timing of the disintegration of Jakobshavn Isbrae's floating tongue and observed ocean heat increase in Disko Bay. The seasonality of the maximum onshore heat flux differs due to distance away from the Irminger Sea. Ocean temperatures near the northwestern coast and southeastern coast respond differently to changes in meltwater from Greenland and high-frequency atmospheric phenomena. With a doubling of the GrIS meltwater, Baffin Bay troughs transported ∼20 % more heat towards the coast. Fewer storms resulted in a doubling of onshore heat through Helheim Glacier's trough. These results demonstrate the regional variability of onshore heat transport through troughs and its potential implications to the GrIS.
Highlights
The Greenland Ice Sheet (GrIS), with the second-largest storage of fresh ice on Earth, has a glaciated cover of 1.81 million square kilometres (Rastner et al, 2012)
The oceanic heat available in Greenland’s troughs is dependent on the location of the trough, source of the warm water origin, how the water is transformed as it travels to the troughs, and local processes such as heat loss to the atmosphere
It is important to understand the processes that bring this warm water to the shelf and into the troughs, as this water can be exchanged into the fjords
Summary
The Greenland Ice Sheet (GrIS), with the second-largest storage of fresh ice on Earth, has a glaciated cover of 1.81 million square kilometres (Rastner et al, 2012). With the volume of ice reaching 2.96 million cubic kilometres, if the entire ice sheet were to melt, the sea level equivalent (SLE) would be ∼ 7 m (Bamber et al, 2013). Analysis of the GrIS’s mass loss and equivalent sea level rise (SLR) has shown that the GrIS has recently become a major source of global mean SLR (van den Broeke et al, 2016). A weakening of the deep water formation may impact the Atlantic Meridional Overturning Circulation (AMOC), influencing how the Earth distributes heat, impacting sea ice production and concentration of dissolved gases such as oxygen and carbon dioxide, and altering ecosystems (Weijer et al, 2012; Swingedouw et al, 2014; Böning et al, 2016; Arrigo et al, 2017)
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