The annual glaciohydrology cycle in the ablation zone of the Greenland ice sheet: Part 1. Hydrology model

William Colgan, Harihar Rajaram, Robert Anderson, Konrad Steffen, Thomas Phillips, Ian Joughin, H. Jay Zwally, Waleed Abdalati

Publikation: Bidrag til tidsskriftArtikelForskningpeer review

43 Citationer (Scopus)


We apply a novel one-dimensional glacier hydrology model that calculates hydraulic head to the tidewater-terminating Sermeq Avannarleq flowline of the Greenland ice sheet. Within a plausible parameter space, the model achieves a quasi-steady-state annual cycle in which hydraulic head oscillates close to flotation throughout the ablation zone. Flotation is briefly achieved during the summer melt season along a ∼17 km stretch of the ∼50 km of flowline within the ablation zone. Beneath the majority of the flowline, subglacial conduit storage 'closes' (i.e. obtains minimum radius) during the winter and 'opens' (i.e. obtains maximum radius) during the summer. Along certain stretches of the flowline, the model predicts that subglacial conduit storage remains open throughout the year. A calculated mean glacier water residence time of ∼2.2 years implies that significant amounts of water are stored in the glacier throughout the year. We interpret this residence time as being indicative of the timescale over which the glacier hydrologic system is capable of adjusting to external surface meltwater forcings. Based on in situ ice velocity observations, we suggest that the summer speed-up event generally corresponds to conditions of increasing hydraulic head during inefficient subglacial drainage. Conversely, the slowdown during fall generally corresponds to conditions of decreasing hydraulic head during efficient subglacial drainage.

Sider (fra-til)697-709
Antal sider13
TidsskriftJournal of Glaciology
Udgave nummer204
StatusUdgivet - sep. 2011
Udgivet eksterntJa


  • Programområde 5: Natur og klima


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