Characterizing the Dynamics of Otto Glacier, Ellesmere Island, Canadian High Arctic: 1992-2020

Abstract

The mass loss observed from glaciers in the Canadian Arctic is unprecedented over recent decades (Hugonnet et al., 2021) and is the third largest contributor to global sea level rise (Derksen et al., 2019). One way in which glaciers lose mass to the ocean is through dynamic discharge, which involves the calving of icebergs to the ocean. Glacier dynamics in the Canadian Arctic have undergone limited study, especially surge-type glaciers, which oscillate between periods of fast flow and slow flow. Detailed studies of individual surge-type glaciers can enhance knowledge of how and why glaciers surge. As such, this thesis analyzed the surge cycle of Otto Glacier on northern Ellesmere Island in Nunavut, Canada, from 1992-2020. The analysis included velocity measurements from 1992-2020, which used data from optical and radar imagery. Three phases were identified for the study period: the fast flow phase (1992-2008), the deceleration phase (2009-2017), and the quiescent phase (2018-2020). Maximum velocities occurred within the lowermost ~6 km of the glacier during the fast flow phase (700-1300 m/yr), and minimum velocities (1-80 m/yr) were noted along the entire glacier during the quiescent phase. Terminus extent, analyzed with optical and radar imagery, advanced by 1545 m during the fast flow phase, and retreated by 1408 m by the end of the quiescent phase. Rates of glacier surface elevation change, obtained from pre-generated elevation products by Hugonnet et al. (2021), showed surface elevation lowering in the lowermost ~6 km of the glacier and thickening upglacier that was progressive over the study period. Analysis of bedrock topography found a v-shaped sill spanning ~4-8 km upglacier from the terminus, which was inferred to have influenced terminus retreat, glacier thickness, and subsequently velocity variability. The findings provide a detailed characterization of the surge cycle phases for Otto Glacier and suggest a possible surge mechanism, which has not previously been explored in depth.