Drivers for Atlantic-origin waters abutting Greenland

Abstract

Abstract. The oceanic heat available in Greenland’s troughs is dependent on the location of the trough, the warm water origin, and how the water is impacted by local processes. This study investigates the mechanisms that bring warm water to the shelf and into the troughs abutting the Greenland Ice Sheet (GrIS). Warm water that is exchanged from the trough into the fjord may influence the melt on the marine terminating glaciers. Regional ocean model experiments showed that Melville Bay troughs experienced warming following 2009. An increase in ocean heat in these troughs may drive a retreat of the GrIS. In 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. Warm Irminger water can extend far north into Baffin Bay, reaching as north as Melville Bay troughs. However, it diminishes north of 67° N on the east coast. Seasonality of the maximum onshore heat flux differs due to distance away from the original source. The north-west coast and south-east coast respond differently to changes in meltwater from Greenland and high frequency atmospheric phenomena. With a doubling of the GrIS meltwater, Baffin Bay troughs brought ∼40 % more heat. The lack of presence of storms resulted in an increase in heat flux (∼20 %) through Helheim glacier’s trough. These results demonstrate the importance of onshore heat transport through troughs and its potential implications to the GrIS.

Mechanisms of Heat Flux Across the Southern Greenland Continental Shelf in 1/10° and 1/12° Ocean/Sea Ice Simulations

“…The maximum heat content in the Wide Shelf region occurs in September in both simulations; this is in general agreement with Gillard et al. (2020) who found the summer months (July‐August) to be the warmest time of year in the Helheim Troughs (near the Sermilik Troughs) and the fall months (September‐November) to be the warmest time of year in Kangerdlugssuaq trough. For both the Narrow and Wide shelf, the difference in the annual average heat content between POP and HYCOM is less than what was found based on the MEOP profiles alone.…”

“…The present study expands on the underlying theory of Gillard et al. (2020) by looking not just at specific troughs but the entire southern Greenland continental shelf.…”

“…Neither simulation includes a representation of GIS meltwater, which has implications for heat fluxes onto the shelf, as was explored by Gillard et al. (2020). The addition of meltwater from the ice sheet has been shown to strengthen currents and increase heat content on the West Greenland shelf within Baffin Bay (Castro de la Guardia et al., 2015; Grivault et al., 2017).…”

“…Gillard et al. (2020) took a comprehensive approach to studying the heat fluxes into specific troughs in east and west Greenland. They found that the seasonal peak in the heat content of the troughs was linked to the distance from the Irminger Sea, indicating the importance of Irminger Water as a source of heat for west Greenland troughs as well as east Greenland troughs.…”