Bed topography and fjord bathymetry mapping

Marine-terminating glaciers dominate the evolution of the Greenland Ice Sheet (GrIS) and its contribution to sea-level rise. Widespread glacier acceleration has been linked to the warming of ocean waters around the periphery of Greenland but a lack of information on the bathymetry of the continental shelf and glacial fjords has limited our ability to understand how subsurface, warm, salty ocean waters of Atlantic origin (AW) reach the glaciers and melt them from below. Here, we employ high-resolution, airborne gravity data (AIRGrav) in combination with multibeam echo sounding (MBES) data, to infer the bathymetry of the coastal areas of Greenland and the ice-ocean transition boundaries where other approaches have traditionally failed.

Greenland Basal Topography (BedMachine v3) Morlighem et al., GRL, 2017

How could we know the ocean has impacts on glacier dynamics?

Most of glaciers in Greenland are marine-terminating glaciers, which means glaciers end in the ocean. There are two types of them. A fjord is a deep trough of sea floor in front of the tidewater glaciers or underneath the floating ice shelves. Water circulation in a fjord is controlled by the fjord’s geometry, including its width, depth and presence or absence of shallow hills (bumps). The depth from the mean sea level to the sea floor, we call it fjord bathymetry. Bed topography is the elevation of the bed rock underneath the glaciers. The trough was carved by former glaciers because the Greenland ice sheet used to be much further advanced during the last glacier maximum. But now the glacier retreat and leave a fjord filled by seawater.The bathymetry controls the a ccess of warm water through deep pathways toward the glacier grounding line.The bed topography beneath the Greenland Ice Sheet controls the flow of ice and its discharge into the ocean. Therefore, good bathymetry and bed elevation data near the GL will help us to understand how the ocean interact with glaciers.

Straneo et al., 2013

Related publications

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