Greenland ice-sheet wide glacier classification based on two distinct seasonal ice velocity behaviors

Saurabh Vijay,Shfaqat Abbas Khan,Brice Noël,Anne M Solgaard,Ian M Howat,Michalea D King

doi:10.1017/jog.2021.89

Abstract

AbstractGreenland glaciers exhibit variable seasonal velocity signals that may reflect differences in subglacial hydrology. Here, we conduct a first GrIS-wide glacier classification based on seasonal velocity patterns derived from 2017 Sentinel-1 radar data. Our classification focuses on two distinct seasonal ice velocity patterns, with the first (type-2 from Moon and others, 2014) showing periods of both speedup and slowdown during the melt season, and the second (type-3) instead showing a longer period of slowdown from elevated velocities in the winter and spring. We analyze 221 glaciers in 2017 and show that 48 exhibit type-2 behavior, and 72 exhibit type-3 behavior. We extend the classification to 2018 and 2019 and find that while the glaciers meeting each criterion vary year to year, type-2 is consistently more common in the northern regions and type-3 is more common in the south. Our results highlight the varied impact of meltwater on subglacial drainage systems and glacier flow in Greenland.

Highlights

The Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate due to a combination of increases in solid ice discharge from marine-terminating glaciers and surface meltwater runoff since the 1990s (Meredith and others, 2019; King and others, 2020; Shepherd and others, 2020)
We propose a semi-automatic scheme to provide first of its kind ice-sheet wide classification of 221 Greenland glaciers in 2017– 2019 based on two distinct seasonal ice velocity patterns
These behaviors are possibly linked with variations in subglacial hydrological conditions due to surface meltwater runoff

Summary

Introduction

The Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate due to a combination of increases in solid ice discharge from marine-terminating glaciers and surface meltwater runoff since the 1990s (Meredith and others, 2019; King and others, 2020; Shepherd and others, 2020). Ice velocities of Greenland glaciers are known to vary at different spatiotemporal scales due to a mixed influence of changing atmospheric, oceanic and local geometric conditions (Khan and others, 2014). These influencing factors include summertime production of surface meltwater (Bevan and others, 2015; Kehrl and others, 2017; Rathmann and others, 2017; Lemos and others, 2018), ice frontal changes (Howat and others, 2008, 2010; Moon and others, 2014; King and others, 2018; Bevan and others, 2019) and seasonal mélange break up (Rathmann and others, 2017). The individual seasonal behaviors, and their changes through time, of most Greenland glaciers, are unknown

Results

Discussion

Conclusion