A5083133820- Cryospheric studies and observations
- Climate change and permafrost
- Arctic and Antarctic ice dynamics
- Winter Sports Injuries and Performance
- Landslides and related hazards
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Hydrology and Watershed Management Studies
- Peatlands and Wetlands Ecology
- Climate variability and models
- Atmospheric and Environmental Gas Dynamics
- Polar Research and Ecology
- Indigenous Studies and Ecology
- Seismology and Earthquake Studies
- Marine animal studies overview
- Hydrocarbon exploration and reservoir analysis
University of Cambridge
2011-2022
Scientific Committee on Antarctic Research
2007-2022
Centre for Polar Observation and Modelling
2003-2007
Abstract. Knowledge of the ice thickness distribution glaciers and caps is an important prerequisite for many glaciological hydrological investigations. A wealth approaches has recently been presented inferring from characteristics surface. With Ice Thickness Models Intercomparison eXperiment (ITMIX) we performed first coordinated assessment quantifying individual model performance. set 17 different models showed that estimates can differ considerably – locally by a spread comparable to...
Abstract In the Northern Hemisphere, ~1500 glaciers, accounting for 28% of glacierized area outside Greenland Ice Sheet, terminate in ocean. Glacier mass loss at their ice-ocean interface, known as frontal ablation, has not yet been comprehensively quantified. Here, we estimate decadal ablation from measurements ice discharge and terminus position change 2000 to 2020. We bias-correct cross-validate estimates uncertainties using independent sources. Frontal marine-terminating glaciers...
Abstract. Hydrographic data acquired in Kangerdlugssuaq Fjord and adjacent seas 1993 2004 are used together with reanalysis from the NEMO ocean modelling framework to elucidate water-mass change ice-ocean-atmosphere interactions East Greenland. The hydrographic show that fjord contains warm subtropical waters were considerably warmer than 1993. shows properties of related a major peak oceanic shoreward heat flux into cross-shelf trough on outer continental shelf. this varies according...
Satellite radar interferometry, 60 MHz airborne ice‐penetrating data, and visible band satellite imagery were used to calculate the velocity structure, ice thickness, changing ice‐marginal extent of Austfonna (8000 km 2 2500 3 ), largest cap in Eurasian Arctic. Ice motion is generally less than about 10 m a −1 , except where faster flowing curvilinear features with velocities several tens over 200 are present. Most drainage basins have undergone retreat past few decades at an average meters...
Abstract Subglacial lakes are an established and important component of the basal hydrological system Antarctic ice sheets, but none have been reported from Greenland. Here we present airborne radio echo sounder (RES) measurements that provide first clear evidence for existence subglacial in Two lakes, with areas ~8 ~10 km 2 , found northwest sector sheet, ~40 margin, below 757 809 m ice, respectively. The setting Greenland differs those being beneath relatively thin cold pointing to a...
Abstract Recent studies indicate an increase in glacier mass loss from the Canadian Arctic Archipelago as a result of warmer summer air temperatures. However, no complete assessment dynamic ice discharge this region exists. We present first surface velocity mapping all masses Queen Elizabeth Islands and show that these discharged ~2.6 ± 0.8 Gt −1 to oceans winter 2012. Approximately 50% was channeled through non surge‐type Trinity Wykeham Glaciers alone. Dynamic Mittie Glacier varied 0.90...
Abstract We use satellite observations to document rapid acceleration and ice loss from a formerly slow‐flowing, marine‐based sector of Austfonna, the largest cap in Eurasian Arctic. During past two decades, discharge has increased 45‐fold, velocity regime switched predominantly slow (~ 10 1 m/yr) fast 3 flow, rates thinning have exceeded 25 m/yr. At time widespread dynamic activation, parts terminus may been near floatation. Subsequently, imbalance propagated 50 km inland within 8 summit....
Abstract We present a first version of the Svalbard ice‐free topography (SVIFT1.0) using mass conserving approach for mapping glacier ice thickness. SVIFT1.0 is informed by more than 1 million point measurements, totalling 8,700 km thickness profiles. publicly available and represents geometric state around year 2010. Our estimate total volume 6,199 3 , equivalent to 1.5‐cm sea level rise. The map suggests that 13% glacierized area grounded below level. A complementary error estimates...
In this study, 3370 km of 100 MHz ice‐penetrating radar data were acquired from Devon Ice Cap, Arctic Canada. Bed returns obtained >90% flight tracks. Mean crossing point errors in ice surface elevation and thickness 7–8 m. Digital models cap bed elevation, thickness, produced can be used as boundary conditions numerical modeling. including 1960 2 contiguous stagnant to its west, is 14,010 . The proper 12,050 Its largest drainage basin 2630 crest has a maximum measured 1921 Maximum...
Abstract The surface velocity field of Devon Ice Cap, Nunavut, Canada, was mapped using interferometric synthetic aperture radar (InSAR). Ascending European Remote-sensing Satellite 1 and 2 (ERS-1/-2) tandem mode data were used for the western southeast sectors, 3 day repeat pass ERS-1 imagery northeast sector. Speckle-tracking procedures with RADARSAT to obtain velocities over terminus Belcher Glacier (a major calving front) where decorrelation between ERS occurred. InSAR highlight a...
Abstract. The basal topography is largely unknown beneath most glaciers and ice caps, many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present two-step reconstruction approach for that solves mass conservation over single or several connected drainage basins. applied variety of test geometries with abundant measurements including marine- land-terminating as well 2400 km2 cap on Svalbard. input requirements are kept...
Abstract. A map of Greenland in the 13th edition (2011) Times Comprehensive Atlas World made headlines because publisher's media release mistakenly stated that permanent ice cover had shrunk 15% since previous 10th (1999) revision. The claimed shrinkage was immediately challenged by glaciologists, then retracted publisher. Here we show: (1) accurate maps extent based on 1978/87 aerial surveys and recent MODIS imagery; (2) at 0.019% a−1 ~50 000 km2 a part east is shown as ice-free Atlas.
ABSTRACT Feature tracking of approximately annually separated Landsat-7 ETM+ imagery acquired from 1999 to 2010 and speckle 24-day RADARSAT-2 2009 2015 reveal that motion the major tidewater glaciers Devon Ice Cap is more variable than previously described. The flow almost half (six 14) outlet slowed over observation period, while terminus regions three 14 sped up in most recent years observation. North Croker Bay Glacier southern showed greatest variability motion, oscillating between...
Abstract Optical satellite imagery was used to estimate glacier surface velocities and iceberg calving rates from Agassiz western Grant Ice Caps, Nunavut, Canada, between 1999 2003. The largest mean annual ranged ∼400 700 m a −1 , but in the ∼100–200 range were common. Summer up an order of magnitude larger than annually averaged velocities. highest velocity (∼1530 ) measured on floating tongue Lake Tuborg Glacier 19 July August 2001. Calving individual glaciers varied by factor two...
The identification of surge activity is important in assessing the duration active and quiescent phases cycle Svalbard glaciers. Satellite aerial photographic images are used to identify describe form flow Perseibreen, a valley glacier 59 km2 on east coast Spitsbergen. Heavy surface crevassing steep ice front, indicative activity, were first observed Perseibreen April 2002. Examination high resolution (15 m) Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) satellite imagery...
Abstract We determined ice velocities for the Academy of Sciences Ice Cap, Severnaya Zemlya, Russian Arctic, during November 2016–November 2017, by feature-tracking 54 pairs Sentinel-1 synthetic-aperture radar images. Seasonal velocity variations with amplitudes up to 10% yearly-averaged were observed. Shorter-term (<15 d) intra-annual had average and maximum deviations from annual mean 16 32%, respectively. This indicates errors that could be incurred if discharge values a single pair...
Abstract. Knowledge of the ice thickness distribution glaciers and caps is an important prerequisite for many glaciological hydrological investigations. A wealth approaches has recently been presented inferring from characteristics surface. With Ice Thickness Models Intercomparison eXperiment (ITMIX) we performed first coordinated assessment quantifying individual model performance. set 17 different models showed that estimates can differ considerably – locally by a spread comparable to...