Investigating Pulse-Type Glaciers in the Canadian Arctic: A Case Study of the Characteristics of Dobbin Bay Glacier, Parrish Glacier, and Eugenie Glacier within the Agassiz Ice Cap

Abstract

Characterizing irregular glacier dynamics is crucial for understanding the drivers of variations in ice motion, improving glacier dynamic modelling, and projecting future contributions to sea-level rise. The majority of glaciers exhibiting irregular dynamics have been classified as ‘surge-type’ glaciers, even though some glaciers display dynamic behaviour that falls outside the classical definition of surging. One such category is ‘pulse-type’ glaciers, which have been identified as a subset type of glacier surging within the Canadian Arctic. Similar to surge-type glaciers, ‘pulsing glaciers’ experience quiescent and active phases but experience variations of ice motion on shorter timescales, with fluctuations in glacier flow restricted to the terminus region where the bed lies below sea level. Due to the recency of this identification (i.e., first reported in Van Wychen et al., 2016), few studies of ‘pulse-type’ glaciers have been conducted, leaving a gap in the understanding their processes and characteristics. In this study, three previously identified pulse-type glaciers, Dobbin Bay Glacier, Parrish Glacier and Eugenie Glacier, located on Agassiz Ice Cap within the Canadian High Arctic, are studied using measurements of surface elevation, ice flow, terminus position and subglacial topography and are used to investigate and distinguish pulse characteristics from other forms of dynamic instability. Pulse events were identified on Dobbin Bay Glacier from 2004 to 2008, Parrish Glacier from 2004 to 2010, and Eugenie Glacier from before 2000 to 2008. Across all three glaciers, a surface elevation rise of 2-5 m a-1 was observed at regions where subglacial sills or sharp valley turns were present, while downglacier regions experienced surface elevation loss of 2- 4 m a-1. During pulse events, velocities within the pulse region ranged from 500 to 1100 m a-1, compared to upglacier regions, which experienced velocities from 50 - 110 m a-1 during both quiescence and pulse events. These findings refine the current definitions of pulse-type glaciers and provide further insight into irregular glacier dynamics within the Canadian Arctic Archipelago.