Near-glacier surveying of a subglacial discharge plume: Implications for plume parameterizations

• Published in: Geophysical Research Letters
• Main Authors: Jackson, Rebecca H., Shroyer, Emily L., Nash, Jonathan D., Sutherland, David A., Carroll, Dustin, Fried, Mason J., Catania, Ginny A., Bartholomaus, Timothy C., Stearns, Leigh A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2017
• Subjects: Greenland; glacier; Tidewater
• Online Access: http://hdl.handle.net/1808/27327; https://doi.org/10.1002/2017GL073602

At tidewater glaciers, plume dynamics affect submarine melting, fjord circulation, and the mixing of meltwater. Models often rely on buoyant plume theory to parameterize plumes and submarine melting; however, these parameterizations are largely untested due to a dearth of near‐glacier measurements. Here we present a high‐resolution ocean survey by ship and remotely operated boat near the terminus of Kangerlussuup Sermia in west Greenland. These novel observations reveal the 3‐D structure and transport of a near‐surface plume, originating at a large undercut conduit in the glacier terminus, that is inconsistent with axisymmetric plume theory, the most common representation of plumes in ocean‐glacier models. Instead, the observations suggest a wider upwelling plume—a “truncated” line plume of ∼200 m width—with higher entrainment and plume‐driven melt compared to the typical axisymmetric representation. Our results highlight the importance of a subglacial outlet's geometry in controlling plume dynamics, with implications for parameterizing the exchange flow and submarine melt in glacial fjord models. NNX12AP50G