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Moulin density controls the timing of peak pressurization within the Greenland Ice Sheet's subglacial drainage system
  • +5
  • Jessica Mejia,
  • Jason Gulley,
  • Celia Trunz,
  • Matthew David Covington,
  • Timothy Bartholomaus,
  • Charles Breithaupt,
  • Surui Xie,
  • Timothy H Dixon
Jessica Mejia
University at Buffalo

Corresponding Author:[email protected]

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Jason Gulley
University of South Florida
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Celia Trunz
Université de Sherbrooke
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Matthew David Covington
University of Arkansas at Fayetteville
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Timothy Bartholomaus
University of Idaho
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Charles Breithaupt
ExxonMobil
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Surui Xie
University of Houston
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Timothy H Dixon
University of South Florida
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Abstract

Links between hydrology and sliding of the Greenland Ice Sheet (GrIS) are poorly understood. Here, we monitored meltwater’s propagation through the entire glacial hydrologic system for catchments at different elevations by quantifying the lag cascade as daily meltwater pulses traveled through the supraglacial, englacial, and subglacial drainage systems. We found that meltwater’s residence time within supraglacial catchments-depending upon area, snow cover, and degree of channelization-controls the timing of peak moulin head, resulting in the two hour later peak observed at higher-elevations. Unlike at lower elevations where peak moulin head and sliding coincided, at higher elevations peak sliding lagged moulin head by ~2.8 hours. This delay was likely caused by the area’s lower moulin density, which required diurnal pressure oscillations to migrate further away from subglacial conduits to elicit the observed velocity response. These observations highlight the supraglacial drainage system’s control on coupling GrIS hydrology and sliding.