Winter speed-up of quiescent surge-type glaciers in Yukon, Canada

Abstract

Glacier surges often initiate in winter, but the mechanism remains unclear in contrast to the well-known summer speed-up at normal glaciers. To better understand the mechanism, we used radar images to examine spatial-temporal changes in the ice velocity of surge-type glaciers near the border of Alaska and the Yukon, focusing on their quiescent phase. We found significant accelerations in the upstream region from autumn to winter, regardless of surging episodes. Moreover, the winter speed-up propagated from upstream to downstream. Given the absence of surface meltwater input in winter, we suggest the presence of water storage near the base that does not directly connect to the surface, yet can promote basal sliding through increased water pressure. Our findings have implications for the modelling of glacial hydrology in winter, which may help us better understand glacier dynamics

Modern glacier velocities across the Icefield Ranges, St Elias Mountains, and variability at selected glaciers from 1959 to 2012

“…These changes, combined with the profile of strongly increasing down-glacier motion followed by an abrupt deceleration, are indicative of an ongoing surge. This provides the first conclusive evidence that the main trunk of Logan Glacier is surge-type, confirming the suggestion of Post (1969) and Abe and Furuya (2014). Using winter measurements from 2010, Burgess and others (2013a) showed a region of active ice comparable in extent to that found in this study, but with peak velocities of only �240 m a -1 .…”

Resolving Seasonal Ice Velocity of 45 Greenlandic Glaciers With Very High Temporal Details

“…Such an inactive hydrologic system primarily contains water from three sources: basal meltwater, ocean water infiltrating into the subglacial system, and meltwater that did not evacuate through channels during the melt season and was retained in the firn and ice body (Brinkerhoff & O'Neel, 2017). Winter speedup observed at few glacier systems in Yukon, Canada (Abe & Furuya, 2015) and the Karakoram (Quincey et al, 2009) also suggest that winter water storage can promote basal sliding by inducing subglacial water pressure changes. Chu et al (2016) pointed out that glaciers respond differently to the same meltwater input depending on how water reroutes in the subglacial environment.…”

Dynamics of surge‐type glaciers in West Kunlun Shan, Northwestern Tibet

“…To estimate velocity errors, we measured the offsets on stable ground (off glacier) [Pritchard, 2005;Abe and Furuya, 2015] and assumed a linear temporal velocity change. The resulting errors in the velocity were 20-40 m/yr (Table 1) with the exception of tandem pairs; this is due to our assumption of a linear velocity change over the 1 day interval.…”