Anne-Marie Nuttall

Detection of superimposed ice on the glaciers Kongsvegen and Midre Lovénbreen, Svalbard, using SAR satellite imagery

Abstract Superimposed ice forms when meltwater refreezes onto a sub-freezing glacier surface. The accumulation zones of many Arctic glaciers include large areas of superimposed ice, which for mass-balance purposes have to be distinguished from the ablation zone consisting of glacier ice. We examine the ability of synthetic aperture radar (SAR) satellite sensors to detect superimposed ice on the glaciers Kongsvegen and midre Lovénbreen on Svalbard. Structural analysis of ice cores as well as surface observations from these glaciers in 1999 and 2000 provide a spatial record of superimposed ice. Winter SAR images show three distinct zones, which correspond closely to areas of glacier ice, superimposed ice and firn. This is seen very clearly on Kongsvegen, but not as clearly on the much smaller midre Lovénbreen. One possible explanation for the contrasting SAR signal may relate to the differing air-bubble content of firn, superimposed ice and glacier ice. Thin layers of winter-formed superimposed ice (510 cm) in some places are not seen on the SAR images, indicating that a certain thickness is needed for detection. The equilibrium-line altitude cannot be detected since the SAR cannot differentiate old superimposed ice, superimposed ice formed currently in the accumulation area in summer and superimposed ice formed currently in the ablation zone in autumn and winter.

Multiphase formation of superimposed ice during a mass-balance year at a maritime high-Arctic glacier

Meteorological and snow-temperature data from midtre Lovenbreen, Spitsbergen, Svalbard, indicate two distinct annual phases of rapid snowpack warming and superimposed-ice formation in 1998/99. Short periods of positive air temperatures in early winter, lasting up to 36 hours and often coinciding with rainfall, caused rapid glacier-wide melting. Percolating water froze to form superimposed ice on the lower half of the glacier, and wetted-refrozen snow and ice lenses at higher altitudes. The second period of superimposed-ice formation commenced in May/June 1999 and continued for 5 weeks at low altitudes and throughout the summer at high altitudes. These observations at midtre Lovenbreen are typical of Spitsbergen glaciers and reflect the unique climatology of the region. They contrast with those from glaciers in more continental climatic settings where superimposed-ice formation is confined to a single period during summer. There are significant implications for glacier mass balance, with superimposed ice locally comprising up to 20% of winter balances and accounting for ∼16-25% of the annual accumulation. Since projected climatic warming is greatest during the winter months in Arctic regions, superimposed ice may become an increasingly important component of the winter, and potentially the net, balance of Spitsbergen glaciers.

The initiation of glacier surging at Fridtjovbreen, Svalbard

Abstract Glacier surges in Svalbard have long durations and multi-year terminations, but much less is known regarding surge initiation in the archipelago. Fridtjovbreen, a 12 km long glacier in central Spitsbergen, advanced ∼ 2.8 km during a surge in the 1990s at a maximum rate of ∼ 4. 2 m d–1 . Differential dual-azimuth satellite radar interferometry (SRI) is used to produce ten snapshots of three-dimensional surface dynamics and four digital elevation models covering the period October 1991–October 1997. The glacier velocity rose slowly and uniformly until June 1995. It then increased dramatically to a measured maximum of ∼ 2.5 m d–1 during February and May 1996, and by October 1997 it had dropped. We attempt to evaluate errors in the calculated velocities. Systematic errors are evaluated using the apparent displacement of bedrock, ∼0.03 m d–1 . Errors arise from assumptions during processing, for example that ice-flow direction does not change during the surge. Two independent measurements using dual-azimuth processing show the mean absolute change in flow direction was ∼1.2°. This study covers fast-flow initiation and peak flow, but not the deceleration phase. The SRI observations show a progressive acceleration phase to the surge, with no evidence of a surge front propagating down-glacier.

Runoff and drainage pattern derived from digital elevation models, Finsterwalderbreen, Svalbard

Abstract Finsterwalderbreen (77°26’ N, 15° 15’ E) is a 35 km2 polythermal, surge-type glacier in southern Spitsbergen, Svalbard. Extensive field investigations have been carried out on the glacier, including mapping of bed topography by radio-echo soundings, mass-balance measurements and hydrological and meteorological registrations. In this paper we have used surface and bed topography and observations of summer ablation to estimate total runoff and subglacial drainage pattern by means of spatial map analysis in standard geographic information system software. The location and relative importance of the water-channel outlets from the glacier were estimated, as well as the change in drainage pattern over the period 1970–90. The results could be compared to direct observations of drainage pattern and discharge recordings. The analyses indicate that the location of the subglacial channels is dominated by the surface topography and thus that the channels are partly pressurized.

Student Engagement Patterns over the Duration of Level 1 and Level 3 Geography Modules: Influences on Student Attendance, Performance and Use of Online Resources

Greater flexibility in delivery resulting from increased use of e-learning will inevitably change the way university students approach studying. Recent studies have examined relationships between attendance, online learning and performance but findings are inconclusive. One concern is that an unintended consequence of placing lecture resources online may be increased absenteeism possibly leading to decrease in performance. This study explores patterns of student engagement across two geography courses. Findings corroborate the importance of attendance as a predictor of performance, demonstrate how assessment influences study behaviour, particularly online, and provide evidence for a need for integrated blended learning designs.

Temporal variations in flow velocity at Finsterwalderbreen, a Svalbard surge-type glacier

Abstract Inter- and intra-annual velocity variations are well known on alpine glaciers, but their importance for Arctic glaciers has only been recognized more recently. This paper presents flow velocity data from Finsterwalderbreen, a 35 km2 polythermal surge-type glacier in southern Svalbard that is presently ∼100 years into its quiescent phase. Field measurements of glacier surface velocities are available from 1950-52 and 1994-97, and mean velocities for the last decade are estimated for the lower glacier using cables drilled to the glacier bed. These velocities show substantial seasonal variations indicating that basal sliding is an important component of surface velocities and interannual fluctuations of up to 75%, possibly indicating variations in subglacial water storage. Several lines of evidence indicate that this glacier has an extensive subglacial hydrological system, generally considered to be a prerequisite for surge-type glaciers, which is at least partly pressurized. Information on surface morphology from 1898 onwards shows that the glacier has experienced continuous retreat since the last surge in about 1910, and has now retreated ∼1.5 km further back than its previous pre-surge position in 1898. Tracking of moraine loops on terrestrial and aerial photographs acquired over a 100 year period indicates that the surge period of Finsterwalderbreen may be lengthening in response to climate changes.

Geometry change between 1990 and 2003 at Finsterwalderbreen, a Svalbard surge-type glacier, from GPS profiling

Abstract Surface mass-balance and geometry data are key to quantifying the climate response of glaciers, and confidence in data synthesis and model interpretations and forecasts requires data from as wide a range of locations and glacier types as possible. This paper presents measurements of surface elevation change at the Svalbard surge-type glacier Finsterwalderbreen, by comparing a 1990 digital elevation model (DEM) with a surface GPS profile from 2003. The pattern of elevation change is consistent with that previously noted between 1970 and 1990, and reflects the continued quiescent-phase evolution of the glacier, with mass loss in the down-glacier/receiving area of up to –1.25mw.e. a–1, and mass gain in the up-glacier/reservoir area of up to 0.60 mw.e. a–1; the area-weighted, mean change for the whole glacier is 0.19mw.e. a–1. The spatial pattern of elevation increase and decrease is complex, and the boundary between thickening and thinning determined by combining GPS and DEM data does not appear to correspond with the equilibrium-line altitude determined from surface mass-balance measurements. There is no evidence yet of a decrease in the rate of reservoir area build-up driven by mass-balance change resulting from the warmer winter air temperatures, and decreased proportion of snowfall in total precipitation, noted at meteorological stations in Svalbard.

SUSPENDED SEDIMENT DYNAMICS IN THE MORTERATSCH PRO-GLACIAL ZONE, BERNINA ALPS, SWITZERLAND

Abstract. Suspended sediment concentration (SSC) in the Ova da Morteratsch, Switzerland, measured during July 2007 was closely associated with discharge (Q) and showed statistically significant relationships at the p < 0.001 level at the proximal and distal ends of the 600 m pro‐glacial zone. SSC predicted from 10‐minute turbidity records gives a much more detailed insight into SSC fluctuations and identified SSC peaks which do not coincide with discharge peaks. Net (proximal – distal) 10‐minute suspended sediment loads (SSL) are predominantly positive (i.e. suspended sediment is being stored in the reach) for most of the 7–19 July 2007 record. Net (proximal – distal) SSLs correlate closely with discharge for the first part of the record (7–13 July) but from 14 to 19 July suspended sediment exhaustion is in evidence and discrete phases of negative net SSL (i.e. sediment flushing) are likely for up to six hours on three separate days which coincide with phases of high discharge and exhaustion of the glacial suspended sediment sources. Analysis of Q at the Berninabach–Pontresina gauging station (5 km downstream) for the past five years revealed that maximum monthly discharges capable of generating sediment flushing events occur in an average of four months each year. The study emphasises the rapid change in suspended sediment transport and yields with distance from the glacier snout and highlights the importance of measurements as close to the glacier snout as possible if data are to be representative of the glaciated land up‐valley. A better understanding of the processes of sediment exchange and the colonisation and stabilisation of sediment stores by vegetation in such pro‐glacial zones is essential if we are to improve predictions of the impacts of climate change on river sediment dynamics and the subsequent effects on aquatic ecology.

Study goals and procrastination tendencies at different stages of the undergraduate degree

Study goals and effective management of study time are both linked to academic success for undergraduates. Mastery goals in particular are associated with study enjoyment and positive educational outcomes such as conceptual change. Conversely, poor self-regulation, in the form of procrastination, is linked to a range of negative study behaviours. Many researchers have treated goal orientations and procrastination tendency as stable traits and few have examined differences across academic levels. This study reports a cross-sectional measure of study goal orientation and procrastination tendency profiles at different academic levels on two undergraduate programmes. Findings concur with other studies in revealing a significant decline in mastery goals, particularly between the first and second years of study. Procrastination tendency is significantly higher in the second year. Potential causes of these differences and their implications are discussed, alongside considerations for positive learning environments.

Observed run-off and suspended sediment dynamics from a minor glacierized basin in south-west Greenland

This study examined run-off and suspended sediment dynamics in a minor glacierized basin in south-west Greenland. A discharge (Q), turbidity (Tu) and air temperature (Tair) record was maintained for 26 days from 25 July 2009 to 19 August 2009 which was supplemented by 335 water samples analysed for suspended sediment concentration (SSC). Clear diurnal fluctuations in Tair, Q and SSC were observed. Mean Tair rose from 10.2 °C in a sunny clear Phase 1 (days 1–14) to 10.8 °C in a cloudy Phase 2 (days 15–25), mean Q increased from 3.4 m3/s in Phase 1 to 4.8 m3/s in Phase 2 and this significant increase in Q may be explained by fresh snowfall higher on the glaciers melting. Mean sampled SSC was 23 mg/l while mean predicted SSC increased from 34 mg/l in Phase 1 to 45 mg/l in Phase 2 and is assumed to be a direct result of the increased Q in Phase 2 entraining fine sediment from higher up channel banks and bars. The SSC, suspended sediment load and SSY estimated in this study are compared with a growing and updated database of sediment studies in Greenland (where data from sediment transport studies in 16 locations around Greenland are collated).