Seasonality in Terminus Ablation Rates for the Glaciers in Kalaallit Nunaat (Greenland)

Since the 1990s, the Greenland Ice Sheet (GrIS) has undergone accelerated mass loss, with a substantial portion due to the dynamic effects of terminus retreat. Conventional assessments of dynamic mass loss, however often overlook the critical aspect of terminus change, focusing primarily on inland ice flow. In this thesis, I construct and analyze mass loss due to both temporal variations in ice flow and detachment of ice from the glacier terminus, called terminus ablation, for 55 marine-terminating glaciers in Greenland over a ten-year period from 2013 to 2023. I calculated terminus ablation rates using openly accessible data for terminus positions, surface elevation, bed elevation, and glacier speed so that we could facilitate the extension of the terminus ablation time series when more data become available. Throughout the decade, both terminus ablation and discharge increased in the spring at most glaciers, supporting previous observations of coincident terminus retreat and glacier flow acceleration. However, terminus ablation was more irregular than discharge over seasonal to inter-annual time scales, signifying the presence of sporadic ice fluxes into the oceans that differ from what is estimated through discharge time series. Three common variations in terminus ablation were identified: erratic seasonal cycles, consistent seasonal variations, and large inter-annual fluctuations. On grouping glaciers into regions to examine the regional patterns, larger seasonal oscillations in terminus ablation than discharge were observed. Causal links between terminus ablation and discharge could not be inferred from the datasets due in part to variations in temporal resolution of terminus and discharge observations for each glacier and across all study glaciers. However, the larger magnitude and more sporadic variations in terminus ablation with respect to discharge suggest that studies focused on the impacts of varying freshwater input from Greenland's glaciers into the ocean should use terminus ablation time series to accurately capture temporal variations in freshwater fluxes to the oceans.