ABSTRACT: At the terminus of tidewater glaciers an interplay of connected processes result in the melt of ice. From both field and laboratory observations, it has been suggested that both bubbles and sediments could be important yet neglected contributors to ice melt at the submarine tidewater glacier terminus. In the laboratory it has been shown that as glacier ice melts, air trapped in pores inside of the ice is released creating flow transpiration at the boundary and buoyant bubble rise at the ice-ocean interface, leading to increased melt (Wengrove et al.,2023). Additionally, during separate laboratory experiments, sediments entrained in the subglacial discharge plume are shown to increase the entrainment of warm ocean water toward the ice leading to higher melt rates (McConnochie andCenedese, 2023). In July 2024, we made the first ever video observations of both bubbles rising and sediments mixing and falling from a stationary-bolted platform to an Alaskan tidewater glacier terminus at three water depths. We expand upon the laboratory investigations and novel field video observations to investigate the balance of energetics from buoyant bubble rise and dense sediment fall as a function of depth and distance from the subglacial discharge plume. Bubble injection and rise and sediment mixing and fall could affect the choice of the transfer coefficients, drag coefficients, and the functional form to be used in the melt parameterization for tidewater glaciers.

BIO: Dr. Meagan Wengrove is a coastal engineer and scientist who leads the Coastal Boundary Dynamics Research Group at Oregon State University. Meagan joined OSU in 2018 after completing her PhD at the University of New Hampshire in Ocean Engineering. Meagan studies the physics of natural and engineered systems in the context of coastal adaptation and climate change.