Supraglacial Hydrology and Dynamic Changes Through the 2021-2022 Surge of Nàłùdäy (Lowell Glacier), Yukon

Abstract

Nàłùdäy’s (Lowell Glacier) most recent surge had a two-phase initiation, with the first phase beginning in spring 2021 at the terminus following a calving event that took place the previous winter. The second acceleration phase began in fall 2021 with surge velocities peaking in spring 2022, before returning to quiescence by late fall 2022. The total length of streams on the glacier surface pre- to post surge dropped by over 50%, with the resulting supraglacial system transporting water less efficiently. The location of the second acceleration coincides with a clustering of moulins which provided water inputs to a subglacial overdeepening. This surge highlights the connection between supraglacial hydrology and surge dynamics, where surge initiation is driven by water input location and subglacial topography, and supraglacial hydrology is impacted by surface changes driven by ice deformation and basal sliding during the surge.