| Summary: | Mass loss from tidewater glaciers worldwide has increased in recent decades, partially attributed to changes occurring at the ice-ocean interface. The melting of the Greenland and Antarctic Ice Sheets have contributed up 14 mm of sea level rise over the past 20 years, and there remains large uncertainty into how these numbers will evolve into the future. At present, ~one-half of the ice lost annually from the Greenland Ice Sheet is due to frontal ablation, or the combination of submarine melting and iceberg calving, with similar percentages observed in Antarctica and other locations where glaciers reach the ocean. Frontal ablation changes the geometry of a glacier’s terminus, influencing glacier dynamics, the fate of upwelling plumes, and the distribution of submarine meltwater input into the ocean. Directly observing frontal ablation and terminus morphology below the waterline is difficult, however, limiting our understanding of these coupled ice-ocean processes. In this dissertation, I use both remotely sensed and field-based observations to investigate the processes that contribute to tidewater glacier evolution. In Chapter II, I combine 3-D multibeam point clouds of the subsurface ice face at LeConte Glacier, Alaska, with concurrent environmental conditions to show that the terminus morphology is predominately overcut despite high multibeam sonar-derived melt rates. This finding challenges the assumption that tidewater glacier termini are largely undercut during periods of high submarine melting and suggests that important glacier-ocean feedbacks are missing from current submarine melt rate theory. In Chapter III and IV, I examine one currently understudied piece of glacial fjord dynamics – the input of meltwater from ice mélange in the upper layers of the water column. I use field observations collected before and after an ephemeral ice mélange event in front of Kangilliup Sermia, Greenland, to directly investigate the extent to which ice mélange meltwater can modify glacier-adjacent water properties. I ...
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