| Summary: | Recent and on-going retreat of many Northern hemisphere marine-terminating glaciers is contributing significantly to sea level rise. It is driven by poorly understood processes occurring at the ice-ocean interface, such as subglacial discharge into the ocean, turbulent plume dynamics, submarine melting, and iceberg calving. These processes are (1) inherently interdisciplinary, requiring expertise in both glaciology and oceanography and (2) difficult to observe, requiring innovative field techniques and careful site selection. This project will address the relationship between subglacial discharge, turbulent plume dynamics, and submarine melting through a comprehensive field campaign at LeConte Glacier, Alaska, supplemented by a state-of-the-art modeling effort. The field site is ideal because it spans a wide range of forcings on daily to seasonal time scales and because the near-terminus fjord environment is accessible year round. A successful project will provide a unique data set and improved models for projecting contributions to future sea level rise. This project will develop a parameterization of a plume, driven by subglacial discharge, as it interacts with the face of a marine-terminating glacier. This is a goal that has been endorsed by the international community. It will be accomplished by conducting three intensive field campaigns to i. sample the upwelling plume directly with manned and autonomous vessels, ii. measure the downstream impact of the plume on near-terminus fjord circulation, iii. determine subglacial discharge and submarine melt rates, and iv. survey associated changes in glacier terminus dynamics. Subglacial discharge and ambient water properties in the proglacial fjord will be monitored throughout the project in order to provide i. important context for the intensive field campaigns, and ii. a range of parameter space to be explored by a turbulence-resolving hydrodynamic plume model. Data from the intensive field campaigns will be used to validate the plume model, which will then be used to explore the wider range of parameter space that is provided by long-term measurements. The latter will allow investigation of the impact of submarine melting on glacier dynamics over seasonal timescales.
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