Direct Measurements of Melt Rate and Boundary Layer Characteristics at Alaskan Icebergs

• Main Author: Weiss, Kaelan
• Other Authors: Nash, Jonathan D., Wengrove, Meagan E., Pearson, Brodie C., Park, Jihye, Skyllingstad, Eric D., College of Earth, Ocean, and Atmospheric Sciences
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Iceberg*
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/9g54xs410

Marine-terminating glaciers are pathways for terrestrial ice to reach Arctic waters, thereby contributing to sea level rise and changing global circulation patterns. One mechanism for ice loss at these glaciers is submarine melting; however, the common submarine melt parameterization underpredicts ice melt through this mechanism. The discrepancy between observed and modeled melt rate may be due to incomplete modeling of all of the processes driving melt in a geophysical setting. Despite having been applied to the vertical termini of marine-terminating glaciers, the melt rate parameterization remains unconstrained by direct measurements due to the hazards of working at a calving ice face. Fortunately, icebergs provide a natural laboratory for measuring melt rate of glacial ice in realistic fjord conditions. Here we present results from the first set of experiments using a novel ice-mounted instrumentation platform at glacial icebergs. We directly measure submarine melt rate and ice-adjacent ocean conditions to determine the conditions that control melt along the sides of glacial icebergs. At the studied icebergs, melt rates scale loosely with ocean temperature and velocity; however, mean temperature and velocity do not fully capture the melt rate variability, and boundary layer flow variability from large eddies, waves, and iceberg rocking can enhance melt rate. We test the performance of four melt rate parameterizations, and in general, the parameterized melt rates do not match the observations, with accurate predictions made solely by the 3-equation parameterization under ideal forcing conditions. While little is currently known about the details of ice-adjacent flow along the faces of marine-terminating glaciers, a melt rate parameterization that incorporates the effects of non-stationary flow variability may increase the accuracy of glacial melt rate predictions.