A5053385922- Cryospheric studies and observations
- Winter Sports Injuries and Performance
- Climate change and permafrost
- Arctic and Antarctic ice dynamics
- Geology and Paleoclimatology Research
- Landslides and related hazards
- Polar Research and Ecology
- Methane Hydrates and Related Phenomena
- Atmospheric and Environmental Gas Dynamics
- Geological Studies and Exploration
- Geophysics and Gravity Measurements
- Soil erosion and sediment transport
- Tree-ring climate responses
- Invertebrate Taxonomy and Ecology
- Adventure Sports and Sensation Seeking
- High Altitude and Hypoxia
- Coastal and Marine Dynamics
- Peatlands and Wetlands Ecology
- Indigenous Studies and Ecology
University of Sheffield
2016-2025
University of Edinburgh
2011-2013
University of Aberdeen
2010-2011
At Bristol
2008
University of Bristol
2007
High resolution measurements of ice motion along a ∼120 km transect in land‐terminating section the GrIS reveal short‐term velocity variations (<1 day), which are forced by rapid meltwater input to subglacial drainage system from sheet surface. The seasonal changes at low elevations (<1000 m) dominated events lasting 1 day week, although daily cycles largely absent higher elevations, reflecting different patterns input. Using simple model conduit behavior we show that record can be...
[1] We measure hydrological parameters in meltwater draining from an outlet glacier west Greenland to investigate seasonal changes the structure and behaviour of system a large catchment ice sheet (GrIS). Our data reveal upglacier expansion increase hydraulic efficiency subglacial drainage system, across >600 km2, distances >50 km ice-sheet margin. This occurs episodically response surface meltwaters into hitherto inefficient as new input locations become active progressively further...
We present subdaily ice flow measurements at four GPS sites between 36 and 72 km from the margin of a marine-terminating Greenland outlet glacier spanning 2009 melt season.Our data show that >35 margin, seasonal shorter-time scale variations are controlled by surface melt-induced changes in subglacial hydrology.Following onset melting each site, motion increased above background for up to 2 months with resultant up-glacier migration both peak acceleration.Later our survey, all decreased...
Research Article| April 01, 2012 Rapid erosion beneath the Greenland ice sheet T. Cowton; Cowton 1School of Geosciences, University Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK Search for other works by this author on: GSW Google Scholar P. Nienow; Nienow I. Bartholomew; Bartholomew A. Sole; Sole D. Mair 2School Aberdeen, Aberdeen AB24 3UF, Geology (2012) 40 (4): 343–346. https://doi.org/10.1130/G32687.1 Article history received: 26 Jul 2011 rev-recd: 04 Nov accepted: 15 first online:...
Abstract We present ice velocities from a land‐terminating transect extending >115 km into the western Greenland Ice Sheet during three contrasting melt years (2009–2011) to determine whether enhanced melting accelerates dynamic mass loss. find no significant correlation between surface and annual flow. There is however positive summer displacement, but negative with winter displacement. This response consistent hydro‐dynamic coupling; flow results longer periods of increasing greater...
Abstract The injection at depth of ice sheet runoff into fjords may be an important control on the frontal melt rate tidewater glaciers. Here we develop a new parameterization for marginal plumes within Massachusetts Institute Technology General Circulation Model (MITgcm), allowing three‐dimensional simulation large (500 km 2 ) glacial annual (or longer) time scales. We find that idealized fjord (without shelf‐driven circulation), subglacial produces thin, strong, and warm down‐fjord current...
The influence of meltwater on the dynamics and geomorphic impact Greenland Ice Sheet is strongly controlled by morphology ice sheet's drainage system. However, this system its evolution through melt season remain poorly understood. Here we present results an intensive programme dye tracing experiments undertaken along lower 14 km a land‐terminating Greenlandic outlet glacier over period four months during 2010 season. These data are interpreted in conjunction with observations proglacial...
Abstract Submarine melting of Greenlandic tidewater glacier termini is proposed as a possible mechanism driving their recent thinning and retreat. We use general circulation model, MITgcm, to simulate water driven by subglacial discharge at the terminus an idealized glacier. vary spatial distribution emerging grounding line examine effect on submarine melt volume distribution. find that hydrology exerts important control melting; under certain conditions distributed system can induce factor...
This review discusses the role that meltwater plays within Greenland ice sheet system. The sheet's hydrology is important because it affects mass balance through its impact on runoff processes and dynamics. considers recent advances in our understanding of storage routing water supraglacial, englacial, subglacial components system their implications for sheet. There have been dramatic increases surface generation since early 1990s, both due to increased air temperatures decreasing albedo....
Glacial meltwater runoff is likely an important source of limiting nutrients for downstream primary producers.This has particular significance regions surrounding the Greenland Ice Sheet, which discharges >400 km 3 annually.The Arctic warming rapidly but impact higher discharge on nutrient export unknown.We present four years hydrological and geochemical data from a large Sheet catchment that includes two highest melt record (2010, 2012).Measurements reveal significant variation in dissolved...
We assess the effect of enhanced basal sliding on flow and mass budget Greenland ice sheet, using a newly developed parameterization relation between meltwater runoff flow. A wide range observations suggest that water generated by melt at surface sheet reaches its bed both fracture drainage through moulins. Once bed, this is likely to affect lubrication, although current are insufficient determine whether changes in subglacial hydraulics will limit potential for speedup An uncertainty...
Abstract Atmospheric warming is increasing surface melting across the Antarctic Peninsula, with unknown impacts upon glacier dynamics at ice-bed interface. Using high-resolution satellite-derived ice velocity data, optical satellite imagery and regional climate modelling, we show that drainage of meltwater to bed outlet glaciers on Peninsula occurs triggers rapid flow accelerations (up 100% greater than annual mean). This provides a mechanism for this sector Ice Sheet respond rapidly...
Abstract. Warm, subtropical-originating Atlantic water (AW) has been identified as a primary driver of mass loss across the marine sectors Greenland Ice Sheet (GrIS), yet specific processes by which this interacts with and erodes calving front tidewater glaciers is frequently modelled much speculated upon but remains largely unobserved. We present suite fjord salinity, temperature, turbidity versus depth casts along glacial runoff estimation from Rink Store glaciers, two major outlets...
Coupling between runoff, hydrology, basal motion and mass loss ('hydrology-dynamics') is a critical component of the Greenland Ice Sheet system. Despite considerable research effort, mechanisms by which runoff influences ice dynamics net long-term (decadal longer) dynamical effect variations in timing magnitude delivery to bed remain subject debate. We synthesise key into land-terminating sheet hydrology-dynamics, order reconcile several apparent contradictions that have recently arisen as...
Significance During summer, meltwater generated on the Greenland ice sheet surface accesses bed, lubricating basal motion and resulting in periods of faster flow. However, net impact varying volumes upon seasonal annual flow, thus sea level rise, remains unclear. In 2012, despite record runoff, including two extreme melt events, at a land-terminating margin flowed more slowly than average year 2009, due principally to slower winter flow following summer Our findings suggest that margins...
Abstract Few subglacial lakes have been identified beneath the Greenland Ice Sheet (GrIS) despite extensive documentation in Antarctica, where periodic release of water can impact ice flow. Here we present an ice-sheet-wide survey lakes, identifying 54 candidates from airborne radio-echo sounding, and 2 ice-surface elevation changes. These range 0.2–5.9 km length, are mostly distributed away divides, relatively slow-moving ice. Based on our results previous observations, suggest three zones...
Predicting the retreat of tidewater outlet glaciers forms a major obstacle to forecasting rate mass loss from Greenland Ice Sheet. This reflects challenges modeling highly dynamic, topographically complex, and data-poor environment glacier-fjord systems that link ice sheet ocean. To avoid these difficulties, we investigate extent which glacier can be explained by simple variables: air temperature, meltwater runoff, ocean two parameterizations "ocean/atmosphere" forcing based on combined...
Abstract. Marine-terminating outlet glacier terminus traces, mapped from satellite and aerial imagery, have been used extensively in understanding how glaciers adjust to climate change variability over a range of timescales. Numerous studies digitized termini manually, but this process is labor intensive, no consistent approach exists. A lack coordination leads duplication efforts, particularly for Greenland, which major scientific research focus. At the same time, machine learning...
Abstract. Nitrogen inputs and microbial nitrogen cycling were investigated along a 79 km transect into the Greenland Ice Sheet (GrIS) during main ablation season in summer 2010. The depletion of dissolved nitrate production ammonium (relative to icemelt) cryoconite holes on Leverett Glacier, within 7.5 ice sheet margin, suggested uptake ammonification respectively. Positive situ acetylene assays indicated fixation both debris-rich 100 m marginal zone up 5.7 upslope Glacier (with rates 16.3...
Abstract Supraglacial lakes can drain to the bed of ice sheets, affecting dynamics, or over their surface, relocating surface water. Focusing on drainage, we first discuss observations lake drainage. In particular, for time, are observed >70 km across Nivlisen shelf, East Antarctica. Inspired by these observations, develop a model drainage through channel that incises into an ice-sheet frictional heat dissipated in flow. Modelled be stable unstable. During rate lake-level drawdown exceeds...