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Physical Geography / Environmental Science PhD Opportunities

Research clusters, groups and topics

Physical Geography / Environmental Science research at the Department of Geography is divided into two broad research clusters: 1) Glaciology and Quaternary and 2) Environmental Processes. Within each of these large clusters, there are several distinct research groups advertising PhD topics suitable for studentships. If you have other ideas for topics that fall within the interests of these research groups, then we would be pleased to discuss them with you. To find out more about the topics or to discuss your own research ideas with a potential supervisor, please contact the relevant supervisor by e-mail.

Enquiries, applications and admissions

We welcome enquiries and applications from those with backgrounds in Physical Geography or Environmental Science, or in any other related and relevant discipline (e.g. Biology, Chemistry, Climatology, Computing, Engineering, Geology, Mathematics, Oceanography or Physics). Applicants should hold, or expect shortly to obtain, at least an Upper Second Class Honours Degree or equivalent.

1. Glaciology and Quaternary - www.geog.cam.ac.uk/research/gqc/

A. Glaciology

A1. Mass balance of Icelandic Glaciers

Supervisors: Ian Willis, Neil Arnold and Gareth Rees

Iceland is especially sensitive to global warming since its climate is affected by the confluence of warm and cold oceanic currents (a branch of the Gulf Stream and the East Greenland current respectively), and the tracks of most N. Atlantic depressions. Small changes in ocean or atmospheric circulation will have large effects on climatic variables such as air temperature, cloudiness and precipitation. Currently, about 11% (11 200km2) of Iceland is covered by ice, mostly contained within extensive plateau ice caps ranging in size from Hofsjökull i Loni (8 km2) to Vatnajökull (8175 km2). The maritime climate means these ice caps receive up to ~4 m w.e. a-1 of snowfall in their accumulation zones and lose up to ~10m w.e. a-1 of ice in their ablation areas. This, together with the fact they are temperate, means they are dynamically responsive to small climatically-induced mass balance changes.

The principal objective of this project is to develop a distributed mass balance – dynamics model for Iceland's glaciers that can be used to calculate spatial variations in accumulation and ablation and predict the likely response of the glaciers' mass balance to future scenarios of climate change. The mass balance component of the model has been used already to simulate surface mass balance variations across Haut Glacier d'Arolla, Switzerland and Midre Lovénbreen, Svalbard and is currently being used to calculate surface mass balance changes across large regions of Svalbard.

A major component to the project would be to couple the current mass balance model to an ice dynamics model. The model will first be developed, applied and tested using data collected on Langjökull, Iceland's second largest icecap (925km2). We have a range of data sets already for this ice mass including surface DEMs (derived from a range of ground dGPS traverse (1997), airborne photogrammetry (2001), and airborne LiDAR (2006)), a bed DEM, and weather station and point mass balance data available since 1996. Airborne Thematic Mapper multispectral data will be used together with Landsat and ground-based reflectance data to develop parameterisations in order to calculate spatial and temporal variations in albedo. 2m resolution airborne LiDAR surface topography data of most of the ice cap and 10cm resolution Terrestrial Laser Scanner surface topography data will be used to parameterise surface roughness. Statistically downscaled ERA-40 reanalysis data and GCM output will be used to drive the model for the past and future respectively. The model will be tested/calibrated against the point mass balance measurements and estimates of volume changes derived from surface DEM comparison. The project will involve further fieldwork in Iceland and benefits from collaboration with Professor Helgi Björnsson, Finnur Pálsson and Sverrir Gudmundsson (University of Iceland) and Dr Richard Hodgkins (University of Loughborough).

A2. Hydrology of polythermal glaciers

Supervisors: Ian Willis, Neil Arnold, Andy Hodson (Sheffield) & Jack Kohler (NVE, Norway)

It is now widely recognised that the hydrology of glaciers controls their dynamics and sediment/solute transfer processes, and the overall river flow regime of glacierised catchments, including the incidence of flooding. Whilst considerable progress has been made in understanding the hydrology of temperate glaciers and incorporating key processes into time dependent hydrological models, research into the hydrology of polythermal glaciers is still in its infancy and there has been little attempt to study the main processes within a numerical modelling context.

The overall aim of this project is to adapt and build on an existing physically-based distributed model of glacier hydrology. Currently, the model calculates distributed meltwater inputs to a glacier surface using standard energy balance theory and routes the water vertically and laterally through the unsaturated and saturated snowpack using standard snow hydrology theory. Variations in water routing through a network of englacial and subglacial channels in response to variations in surface water inputs are also treated in a physical way.

The model has so far been developed and tested using data from a temperate glacier in Switzerland but will be applied to a polythermal glacier in Svalbard for this project. There will be two main stages of model development. First, the surface energy balance and snow hydrology components of the model will be adapted to ensure they correctly calculate snowpack temperatures, melt rates, conduction within the snowpack and refreezing within the snowpack. Second, the subglacial hydrology component of the model will be adapted to include the effects on water routing of a distributed subglacial drainage system comprising a thin film and/or linked cavities, to account for interactions between the distributed and channelised components, and to incorporate the evolution of the subglacial drainage system to allow for the storage and subsequent release of water, which seems to be a charcateristics of many polythermal glaciers. Existing data sets will be used to develop and test the model, but the project is also likely to contain a fieldwork component at Midre Lovenbreen or Austre Lovenbreen, Svalbard to collect new data.

A3. Surface energy-balance and melt modelling of debris-covered glaciers

Supervisors: I. Willis, N. Arnold and B. Brock (Dundee)

As alpine glaciers retreat, debris, ranging in size from boulders to dust is increasingly concentrated onto their surfaces. Several studies at specific locations on a few glaciers have shown that thin layers of debris may enhance surface melt rates by lowering albedo but that thicker debris layers may reduce ablation by shading. Distributed glacier surface energy balance models do not adequately account for the effects of debris cover and its potential change in the future on patterns of melt and runoff, and yet this is likely to play an increasingly important role over the next few decades with important implications for glacier mass balance and the hydrology of glacier fed streams.

The overall aims of this project are to: i) use a combination of field work and remote sensing image classification techniques to quantify the debris cover changes of certain glaciers of the last few decades; ii) undertake field work on several glaciers to collect data necessary to calculate the energy and mass fluxes between the atmosphere and different types of debris covered ice surface and how these vary during an ablation season; iii) adapt an existing distributed energy balance / melt model to incorporate the effects of debris cover and test/calibrate the model against field measurements; iv) use the model to investigate the sensitivity of glacier mass balance and runoff to different debris covers and different formulations of debris cover processes; and v) use the model to evaluate how the debris covers and geometries of glaciers will evolve in the future to different scenarios of climate change.

The project will likely involve fieldwork in the European Alps but also possibly the Southern Alps, New Zealand or Alaska, USA.

A4. Using airborne and spaceborne remote sensing to investigate glacier geomorphic processes

Supervisors: Ian Willis, Gareth Rees and Neil Arnold

Airborne and spaceborne remote sensing techniques are widely used in glaciology to map the former extent of ice masses, and the geomophological features they have left behind. Such data are increasingly being used to infer the dynamic processes of former ice masses, in particular the distribution of warm and cold based ice, the locations of fast and slow flow, and the regions of basal sliding vs. sediment deformation. In a similar way, the technique of swath bathymetry is increasingly being used to map the geomorphology and reconstruct processes of former ice masses that terminated in shallow marine environments.

This project will use a combination of airborne and spaceborne remotely sensed imagery, together with airborne topopgraphic LiDAR data to investigate the geomorphology and retreat history of formerly glaciated terrain. We already have such data collected from several Svalbard glaciers in 2003 and 2005, several Icelandic glaciers in 2007, and hope to supplement these with flights in the Scottish Highlands in 2009. The LiDAR data have a horizontal resolution of ~1m and a vertical accuracy of ~0.1m and so the data have the potential to reveal detailed glacial geomorphic processes at a scale not previously possible with other remote sensing techniques.

The work will involve a variety of image analysis techniques but there will also be the opportunity for fieldwork in Svalbard and Iceland and (hopefully) the Scottish Highlands involving ground surveying, geomorphic mapping, and sediment logging, for ground-truthing purposes.

A5. Investigating flow sensitivity of Greenland outlet glaciers

Supervisors: Poul Christoffersen and Andreas Vieli (Durham)

Remote sensing of the Greenland Ice Sheet has revealed a net increase in ice-mass loss from 50 to 100 cubic km per year between 1995 and 2000 due to widespread acceleration of ice flow below 66°N. In 2005, the mass loss may have increased to more than 200 km3/year as the geographical boundary of speed-up migrated to 70°N (Rignot and Kanagaratnam, 2006). The sudden increase in sea-level-rise contribution from Greenland glaciers captured the attention of scientists, policymakers and the general public and the need for a better understanding of dynamic controls on ice sheet mass balance is one of the key conclusions in the Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC, 2007).

It is important to identify the driver of ice sheet mass-loss because an annual ice mass loss of 220 Gt corresponds to sea-level rise in excess of 0.6 mm/year. Zwally et al. (2002) measured surface velocities on 1-km-thick ice in West Greenland and proposed that speed-up events were caused by basal lubrication induced by penetration of surface meltwater to the bed. This mechanism may provoke a precarious positive feedback because accelerated ice flow leads to thinning, which in turn may lead to an increase in surface melt since a larger part of the ice-sheet moves into lower and therefore warmer elevations. Recent studies have confirmed this mechanism, but significant impacts are confined to the slow-moving, land-terminating parts of the ice sheet (Das et al., 2008; Joughin et al., 2008). Surface melt-induced basal lubrication does not significantly influence the fast flow of marine outlet glaciers (Joughin et al., 2008). Even on the land-terminating margin, its occurrence appears to have a very limited impact on the annual rate of ice flow (van de Wal et al., 2008). These observations are consistent with mapped ice margins, which show widespread, synchronous recession in 2000-2006 for glaciers terminating in the ocean and no detectable change for glaciers terminating on land (Moon and Joughin, 2008).

The aim of this project is to examine discharge fluctuations from Kangerdlugssuaq and Helheim glaciers in East Greenland. The project will include development and application of a numerical flow model where calving dynamics are influenced by ocean properties (Holland et al., 2008). The performance of the model will be tested on the basis of datasets including (i) meteorological data acquired from automatic weather stations, (ii) time series of speed and calving front position, and (iii) oceanographic measurements from marine-geophysical cruises. The model will be used to explore the nature of ice-ocean-climate interactions and to predict sea-level rise associated with glacial discharge from two of Greenland's most significant drainage basins.

A6. Assessing atmospheric and oceanic impacts on Arctic ice caps

Supervisors: Poul Christoffersen and Julian Dowdeswell

The body of scientific evidence for significant anthropogenic impacts on the global climate is growing and public concern underscores a need for better assessments of contemporary environmental changes in regions such as the Arctic. Although the vast majority of ice on Earth is stored in Greenland and Antarctica, it is important to keep in mind that 70% of the cryospheric contribution to 20th century sea-level rise was attributed to the retreat of mountain glaciers and ice caps (Dyurgerov and Meier, 2000; Meier and et al., 2007). Arctic ice masses are an important component of global change, especially as Arctic temperatures are increasing at almost twice the global average (IPCC, 2007).

The aim of this project is to investigate the response of Arctic ice caps to seasonal and interannual variations in air temperature and ocean temperature. The glaciological investigation will include delineation of calving ice fronts in time series and determination of surface velocity using the feature tracking technique. The air and ocean components involve investigation of meteorological records and sea-surface temperatures derived from satellite sensors. The anticipated outcomes from this interdisciplinary project include integrated assessments of atmospheric vs. oceanic forcings and physical understanding of the response of ice caps to weather cycles vs. climate trends. The project can be designed so that it focuses on a specific Arctic ice cap or a selection of Arctic ice caps. The studentship may be integrated with outcomes from a NERC-funded research project that aims to elucidate ice flow and basal conditions on Vestfonna Ice Cap in northeast Svalbard.

A7. Investigating ice flow and meltwater hydraulics on the western margin of the Greenland Ice Sheet

Supervisor: Poul Christoffersen and Ian Willis

The Greenland Ice Sheet rests on bedrock above or close to sea level. Glaciologists have for years assumed that such position would be stable and that demise of the ice sheet would require thousands of years even under global warming scenarios. This assumption needs urgent revision. It was recently shown that surface meltwater can penetrate to the base of the Greenland Ice Sheet and cause ice-flow speed-up due to faster basal sliding (Zwally et al., 2003; Das et al., 2008; Joughin et al., 2008). This mechanism is potentially dangerous because accelerated ice flow leads to thinning, which in turn leads to an increase in surface melt since a larger part of the ice sheet moves into lower and warmer elevations.

Surface meltwater-induced basal mechanics are poorly understood and they are not present in the current generation of ice sheet models used to forecast future sea-level change. As highlighted in the Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC, 2007), it is essential that glaciologists provide a theoretical means to quantitatively evaluate: (1) linkages between surface, interior and basal water systems and their impacts on dynamic processes, and (2) the extent to which Arctic warming will affect the spatial and temporal characteristics of meltwater-induced glacial dynamics.

This project will address the above shortcomings by development and application of a numerical model that integrates ice flow and meltwater drainage in a land-terminating catchment on the western flank of the Greenland Ice Sheet. The project is designed so that it interacts with a multifaceted research project funded by the Natural Environment Research Council. The project may thus involve glaciological investigations with deep-looking (low frequency) radar, automatic weather stations and survey-quality GPS receivers.

A8. Processes and patterns of glacier-influenced sedimentation on Arctic and Antarctic continental margins

Supervisor: Julian Dowdeswell

During Quaternary glacial periods, glaciers and ice sheets expanded along fjords and across continental shelves, sometimes reaching the shelf edge, on many high-latitude margins in the Arctic and Antarctic (e.g. Dowdeswell et al., 2002; Ottesen et al., 2005; Dowdeswell et al., 2006). Submarine landforms, produced by the action of these ice masses, contain a record of the past extent, flow direction and processes that took place at the ice-bed interface. The basal boundary of glaciers and ice sheets is of considerable significance to our understanding of glaciological processes, but it is a location hidden by a kilometre or more of ice in modern polar settings. Glacier and ice sheet retreat after the last glacial period has both revealed suites of submarine landforms produced at the base of former ice masses, and marine waters have protected them from much of the subsequent erosion to which sub-aerial landforms have been subjected.

We hold a large number of geophysical and geological datasets concerning continental shelf, slope and deep-marine high-latitude settings that have been influenced intermittently by the growth and decay of ice masses. These datasets include swath bathymetry, shallow acoustic profiles and core material, that can be used to reconstruct the past form and flow of ice sheets. The candidate would work with several of these datasets, using digital image analysis tools in order to understand the details of past ice flow extent, direction and basal processes. Data are available from the Arctic (Greenland, Svalbard and Norwegian margins) and from West Antarctica and the Antarctic Peninsula. These datasets have been collected over the past decade or so on a series of research cruises of the British ice-strengthened research vessel James Clark Ross, and there will be a further cruise this summer. The successful candidate may be able to take part in this cruise to West Greenland.

A9. Modelling ice flow and sediment transfer by Antarctic ice streams

Supervisor: Poul Christoffersen and Julian Dowdeswell

Satellite remote sensing has provided much new information about the contemporary changes occurring in the Antarctic Ice Sheet. Although the quality of satellite sensors are improving rapidly, these remotely sensed data are ultimately snapshots in time, as coverage is limited to only a few decades. The geological record of the Antarctic continental shelf has been used to infer the history of the Antarctic Ice Sheet, but this approach does not include the physical constraints offered by e.g. numerical modelling techniques.

The aim of this project is to integrate geological processes in a numerical ice flow model (Bougamont et al., 2003; Christoffersen and Tulaczyk, 2003). The integrated model will be applied to an outlet glacier that drains the East Antarctic Ice Sheet and feeds the Ross Ice Shelf. The model will be used to reconstruct ice flow and sediment transfer from the Antarctic continent to the Antarctic continental shelf. Model results will be validated using geological records from the Cape Roberts Projects and ANDRILL (Mosola et al., 2006; McKay et al., 2008).

One of the key objectives of this project is to elucidate spatial and temporal characteristics of sediment entrainment and transfer by Antarctic ice streams. The ice-flow/sediment-transfer model will be used as a means to quantitatively constrain ice flow histories inferred from the geological record. The anticipated outcomes from the project will contribute to a better understanding of the Antarctic Ice Sheet's evolution. Understanding ice sheet dynamics during warm periods in Earth's past is important because it will elucidate the sensitivity of the Antarctic Ice Sheet to climate change including current Anthropogenic impacts.

B. Quaternary Palaeoenvironments - www.qpg.geog.cam.ac.uk

B1. The Upper Cretaceous Chalk of southern and eastern England: changes during Tertiary to modern history

Supervisors: P.L.Gibbard, C.V. Jeans, R.N. Mortimore, J. Dixon, and D. Wray

The White Chalk is the dominant rock type of southern and eastern England as well as the Paris Basin. Human society is becoming increasingly dependent on the Chalk; not only is it the main source of water for huge concentrations of humans in this area, it is also important as the last host rock through which travel, drainage and other services are developed. Cuttings or sub-surface tunnels often cause major engineering problems because of difficulties in predicting the properties of Chalk. In the last twenty years considerable efforts by academic geologists and the British Geological Survey have resulted in the remapping the Chalk into more realistic and engineering-friendly units. These provide a better but still far from perfect prediction of its properties. There are still many features developed during the Chalk's post depositional history that are not understood and therefore cannot be predicted, thus causing major problems to society. The aim of this project is to investigate these features in order to define them geologically and deduce the underlying processes, be they related to varying depth of burial, changing stress fields, freezing and thawing, heat-flow fluctuations, pore water chemistry or changing water tables.

The project will involve considerable fieldwork in England associated with very careful observations. It will concentrate on the deposition of secondary calcium carbonate (mainly calcite) and will involve laboratory methods (petrography, stable isotopes, trace elements) for its characterisation. Relative and absolute methods of dating will be used.

Transferable skills are likely to include:

B2: Middle Pleistocene glacial sedimentation in East Anglia.

Supervisors: P.L.Gibbard, S.Boreham, P.Hughes, & J.Ehlers

The glaciation in the Anglian Stage was one of the most extensive of the Pleistocene. The Anglian glacial sediments are best preserved in Eastern England and the adjacent offshore region include extensive sequences of deposits and features formed during this event. On the basis of strong lithological and detailed stratigraphical relationships the Anglian is equated with the continental Elsterian Stage (=Marine Isotope Stage 12), which is known to have included the most extensive Pleistocene ice sheets in central eastern Europe. In lowland Britain evidence of glaciation is primarily based on lithology and stratigraphy, with glacial episodes being identified by till and glaciofluvial sediments and glacial limits being determined by the extent of these deposits.

In eastern East Anglia the Anglian glaciation is represented by two substantial formations of glaciogenic sediments, the North Sea Drift Formation of Scandinavian and North-Sea floor origin, and the Lowestoft Formation till (Ehlers & Gibbard 1991; Hopson & Bridge, 1987; Lewis 1999; Mitchell et al. 1973; Perrin et al. 1979; Pointon, 1978; Stuart & Lister 2000; West 1980) deposited by British ice, respectively. Intermediate between these two formations are the Corton Sands and associated Leet Hill gravels. There is general agreement that the Corton Sands and the Leet Hill Gravels were derived from the North Sea Drift Formation ice sheet and are therefore of the same age (Banham, 1971, Bridge & Hopson, 1988, Hamblin et al. 2000). Stratigraphically, therefore these two members are genetically related to the North Sea ice and therefore should properly be included in the North Sea Drift Formation.(e.g.. Lunkka, 1994; Lewis 1999)..

The deposition of the Corton Sands has been the subject of much investigation in recent years. Originally they were thought to represent interstadial conditions (cf. Mitchell et al., 1973), however, plant remains within the sands showed that they were of 'full-glacial' affinity. Following Banham (1971), Pointon (1978) and Bridge & Hopson (1985) refined the stratigraphy. Lithological studies and palaeocurrent analyses demonstrate that the sands were derived from the North Sea Drift ice lobe to the N and NW (Bridge& Hopson, 1985; Bridge, 1988 ;Lunkka (1994). The general concensus is that the sands were deposited by meltwater streams flowing in a W to E direction, broadly parallel to the present River Waveney, with an outlet close to Great Yarmouth. Here the streams probably entered a vast freshwater lake forming a delta complex in the southern North Sea basin (Gibbard, 1988, Gibbard et al. 2007; Gibbard 2007). Subsequent advance of the Lowestoft Till ice from the W overode the sequence, and also locally entered the lake.

Recent attempts to reinterpret the Corton Sands (e.g. by Lee et al. 2006) have yielded conflicting and questionable results that do not correspond with earlier conclusions (cf. Gibbard et al. 2007). These conflicting conclusions emphasise the need for a thorough investigation of the deposits' 3-dimensional sedimentology and stratigraphical relationships across the region.

This project will focus on establishing both the glacial events and their implications for sedimentation of the Corton Sands and Leet Hill members. Through this the palaeogeographical and palaeoenvironmental evolution of the region and more particularly, the relationship of the glacier and its meltwater to the North Sea basin lake will be determined. This is a thoroughly field-based project and will require the student to investigate all available exposures of glacial sediments in eastern Suffolk and Norfolk in order to develop a generalised sedimentary/geomorphological sequence for the region. The student will also draw together the borehole archives from the British Geological Survey and related bodies to produce a comprehensive sequence. These approaches will be supported by relative and absolute dating (OSL), if and as appropriate (funding for the dating will be sought separately).

B3. Pleistocene history of the Birmingham district

Supervisors: P.L.Gibbard, S.Boreham, P.Hughes

Lowland southern Britain has experienced at least three, and potentially more, glacial episodes during the Middle and Late Pleistocene (Anglian, Wolstonian, and Devensian stages). However, recent re-evaluation of the record of glaciation and associated events in eastern England has thrown into question the timing and potential equivalents of the glacial sequence.

The West Midlands has been a key area for investigation of Quaternary sequences since the classic work of L.J.Wills (1937) and later F.W.Shotton (1953). These investigations demonstrated that the west Midlands conurbation is built on a complex sequence of Middle Pleistocene-age sediments. In particular, a suite of glacial sediments, that Shotton related to late Middle Pleistocene glaciation, are widespread in the region. He related these glacial sediments to the second glaciation episode (Wolstonian glaciation =Saalian, ?= Marine Isotope Stage (MIS) 6), intermediate in age between the Hoxnian (= Holsteinian,?=MIS 11) and Ipswichian (= Eemian,?=MIS 5e) interglacial Stages.

However, since these proposals there has been uncertainty about their relation to the East Anglian sequence, to the extent that in the 1980s it became increasingly thought that they should be referred to the older, Anglian Stage. Despite this conclusion, a younger Middle Pleistocene glacigenic sequence certainly occurs in the Midlands, Yorkshire and northern East Anglia. Because it seems to have been of similar extent to that in the subsequent Devensian (=Weichselian) Stage, this glacial episode is more poorly represented in the Pleistocene record. Despite decades of research, there remains the difficulty of establishing, beyond doubt, the relationship of the Anglian and Wolstonian glacial and associated sequences in the West Midlands.

In addition, the glacial sequence is intimately related to fluvial and fluvioglacial deposits of rivers associated with north-westward and southward-aligned drainage that has been related to the rivers Thames and Avon, and the postulated Bytham River.

The Birmingham district therefore occupies the critical position for the establishment of these glacial and fluvial sequences in the region. Not only is the city predominantly built on the Middle Pleistocene glacial sequence, but it also lies outside the Devensian glacial limit. Therefore pre-Devensian sediments are relatively undisturbed. Moreover, the Pleistocene sequence of the region includes several very important interglacial marker units at sites including Quinton, Nechells, Waverly Wood, Brandon etc.. The potential for contributing to the elucidation of the later Pleistocene history of the region is therefore substantial. In addition, the potential contribution to the debate on glaciation in lowland Britain is also considerable.

This project will exploit the considerable experience of the supervisors in urban geological investigations. In particular, the vast untapped resource of borehole information will be collated and assessed to determine the Pleistocene geological sequence across the district. This evidence will be supplemented by careful, systematic field investigation of field and construction sites as they become available, together with such quarry and natural exposures as are available in the area. The resulting database will be evaluated and supported by field sampling and laboratory analyses as appropriate to provide the basis of a new Pleistocene history of the district.

B4. Palaeoenvironmental history of glacial lakes in Greece

Supervisors: P.L.Gibbard, P. Hughes, C. Turner

The mountains of Greece were glaciated on several occasions during the Middle and Late Pleistocene (Hughes et al. 2006). Since many of these mountain areas are formed in limestones, there are few glacial lakes. However, some glaciated mountains are formed in impermeable ophiolite rocks, which frequently contain numerous glacial lakes. The oldest glacial deposits in the Pindus Mountains formed during the Middle Pleistocene, and Late Pleistocene glaciation was restricted to the highest cirques. This project will examine lake sedimentary sequences from glacial deposits of unknown age, at various stratigraphical positions in the northern Pindus Mountains. At present, glacial deposits in ophiolite massifs are merely correlated with glacial units in limestone areas, which are dated using uranium-series techniques. In addition to constraining the age of associated glacial deposits, this project will provide detailed palaeoenvironmental reconstructions for the period since glaciation. Recent work has shown that the glaciated ophiolite massifs of the northern Pindus Mountains were exploited by Middle Palaeolithic hunters (Efstratiou et al. 2006). Palaeoenvironmental reconstructions from lake sites present during the last cold stage will contribute important new data toward understand the nature of environments at a time of early human occupation in this area.

The aims of the project are to a) reconstruct the palaeoenvironmental history of these glacial lakes since formation, using pollen analysis and a range of sedimentological techniques; b) determine the age of the onset of deposition in these glacial lakes using geochronological, palaeomagnetic and incremental techniques, and; c) relate the sedimentary successions in these glacial lakes with wider-scale environmental change.

B5. Quaternary development and palaeoenvironments of the Kalamas-Doliana Basin, Epirus, NW Greece

Supervisors: P. Gibbard, C. Turner, P.Hughes

North-western Greece, between the Mediterranean Sea and the high Pindus Mountains, is characterised by a complex series of tectonically controlled basins, separated by small north-south trending mountain ranges. The best known of these basins is that centred around Ioannina and containing Lake Pamvotis, where deep boreholes have provided long Quaternary pollen sequences.

The Kalamas-Doliana basin, to the west of the Ioannina Basin, also contained an extensive lake lasting at least into Middle Pleistocene times until tectonic lowering of the Soulianou Gap allowed the River Kalamas to drain the basin, where it is still excavating a deep gorge through ancient lacustrine sediments. The basin yields many open exposures of Pleistocene lacustrine sediments, particularly calcareous marls, some already known to contain fossil pollen, as well as freshwater molluscan assemblages, ostracods and occasional vertebrate fossils. These present very good opportunities for stratigraphical and palaeoenvironmental interpretation.

The project will require both rigorous fieldwork in rough but beautiful countryside and patient work in the laboratory applying and exploiting a variety of analytical techniques.

2. Environmental Processes - www.geog.cam.ac.uk/research/ep/

C. Cambridge Coastal Research Unit - www.ccru.geog.cam.ac.uk

C1. The decadal morphodynamic change of cuspate forelands: a case study of Winterton Ness, UK.

Supervisors: I Möller & T Spencer

An adequate understanding of, and ability to predict, geomorphological processes that govern the long-term natural and/or human induced changes of large-scale sedimentary features, such as cuspate forelands, is essential to the successful management of shorelines. It has been speculated that some large-scale (km scale) nearshore sedimentary features, the nesses or cuspate forelands, of the UK East Coast are inextricably linked to offshore tidal sand banks and thus to the regional sediment transport on the shores of the southern North Sea as a whole. The highly dynamic nature of these nesses has led to the migration of large amounts of sediment alongshore and resulted in changes of beach width of >100 m over time-spans of less than 40 years (Robinson, 1980). Coastal managers are thus faced with the challenge to understand the link between the dynamics of the nesses and sediment transport on a larger scale within the Southern North Sea. Furthermore, the ability to predict the morphological evolution of such features is required if direct and indirect coastal management problems linked to the movement of nesses are to be anticipated.

The coastal management of sedimentary shorelines requires that the maximum amount of morphodynamic information is extracted from existing datasets. In particular, management applications increasingly require information on sediment volumes (for the determination of sediment budgets) rather than beach plan-form or cross-sectional change. In their attempt to reconstruct ness behaviour, early studies (e.g. McCave, 1978 and Robinson, 1966; 1980) had to rely on topomaps produced infrequently over the past century (with periods of up to several decades between individual surveys) and with a limited resolution for the analysis of beach planform shape parameters. These shortcomings resulted in several, often contradictory, theories as to the evolution and dynamics of these features. Since the early 1990s, annual 1:5,000 aerial stereo-pair photographs have become available that now provide scope for a much more in-depth study of the annual to decadal dynamics of the ness features of the UK East Coast. In addition, new digital methods for the analysis of spatial data (such as digital photogrammetry) have become available. Previous work in Cambridge, as part of an EU-funded project, has shown that such methods can successfully be used to extract three-dimensional morphodynamic information from repeat photography. This in turn has allowed a re-evaluation of existing theories of ness dynamics and evolution.

This project will build upon, and extend, the analysis of aerial photography of Winterton Ness, Norfolk coast, beyond the period 1998 - 2001, to encompass the full 15-year time period (1992 - present) now available. Images, acquired from an agreed collaboration with the UK Environment Agency, will be georeferenced by ground control data acquired by differential GPS (dGPS) field survey. The position of the dune edge and other beach plan-form features will be identified, mapped, and converted into computer-animated time-series. Digital photogrammetry techniques will be applied to those images available in digital format to generate digital elevation models (DEMs). The accuracy of the DEMs will be determined through field surveys using ground-based LiDAR and dGPS. The results will be used to construct animations and quantitative estimates of the morphological change that have characterised Winterton Ness over the 15-year time-scale. This information will then be set in the context of available information on wave/tide circulation patterns and other ongoing research on the UK East Coast and further afield to revise and extend existing models of the evolution of cuspate forelands in general and assess the impact of human interference with long-shore transport along this coast in particular.

C2. Wave energy dissipation and morphological feedbacks in seagrass meadows

Supervisors: T. Spencer & I. Möller

Concern as to the implications of sea level rise and changing wave climates on low-lying sedimentary shores has resulted in an increased need to understand the interaction between biology, sedimentology, and hydrodynamics on such coasts. Recent field and laboratory measurements of tidal current and wave attenuation on upper intertidal saltmarshes have begun to better define these interactions; little is still known about such process interactions in lower intertidal environments.

Seagrass beds often characterize the lower intertidal / upper subtidal zone and relationships between physical factors (water depth, exposure) and seagrass growth/sustainability has been documented by a number of studies. Wave/tide driven current stress can be the dominant factor in restricting seagrass growth but, once present, seagrass meadows also affect local hydrodynamic conditions, sediment availability and patterns of erosion and accretion, both within and landward of the seagrass bed.

Three species of Zostera occur in the UK. Dwarf eelgrass Zostera noltii is found highest on the shore (often adjacent to lower saltmarsh communities), narrow-leaved eelgrass Zostera angustifolia on the mid to lower shore and eelgrass Zostera marina predominantly in the sublittoral zone. Field studies in this project will be undertaken with possible sites in Dorset or in the Cromarty Firth, NE Scotland, which supports the largest total area of dwarf eelgrass and narrow leaved eelgrass in Britain (approximately 1200 ha). Other sites to be investigated will include the Exe Estuary and the Solent marshes.

This study will combine field measurements with laboratory experiments to quantify the impact of individual species of seagrass on incident waves in a series of water depths and for a range of wave conditions. The resulting datasets will be compared to existing datasets in comparable conditions of incident waves over submerged saltmarsh vegetation and will be used to validate existing numerical models of wave energy dissipation through vegetation fields.

C3. Vegetation surface roughness quantification and relationships to flow attenuation over intertidal surfaces

Supervisors: I. Möller & T. Spencer

Successful coastal management in the face of global environmental change (sea level rise and storminess) will require better tools to assess the natural wave/tide 'buffering' function of the intertidal zone. Previous studies have shown that intertidal salt marsh environments in a variety of physical settings can cause significant attenuation of waves (e.g. Möller et al., 2001 and Möller and Spencer, 2003) and currents (e.g. Leonard and Reed, 2002). This research has focussed on either the 'marsh-wide' scale of the complex canopy of mixed vegetation type (100s metre) or on the scale of individual plants and their structure (<1m scale) , involving detailed, time-consuming, and costly field measurements at specific sites. More accurate numerical models of wave and tide propagation across vegetated surfaces would allow for a more generic assessment of the varying sea defence function of the intertidal zone, as is required for the design of scientifically-informed regional coastal management strategies. Currently, however, existing numerical models perform with limited accuracy due to the poor representation of vegetation-induced surface roughness and associated flow retardation.

Many saltmarsh plant species, such as Atriplex portulacoides, present on most UK East coast marshes, not only exhibit a high degree of structural complexity, but are also subject to seasonal changes in growth that may affect their wave/current attenuation potential (Möller and Spencer, 2002). To represent such vegetation simply as an array of rigid cylinders obstructing the flow (Knutson et al. 1982), or to merely quantifying the drag force acting on the plant (Dalrymple et al. 1984, Kobayashi et al. 1993), does thus not suffice as an adequate assessment of hydrodynamic roughness. Furthermore, the flexible and buoyant nature of the intertidal vegetation canopy provides additional challenges when quantifying its hydrodynamic behaviour.

Side-on digital photography (as developed for grasslands by Zehm et al. (2003) and adapted for salt marsh vegetation by Möller (2006)) and ground-based LiDAR offers the possibility of developing more complex statistical summary parameters that represent those characteristics of the vegetation canopy that relate most closely to flow attenuation by the canopy. This study will use both these techniques in a controlled laboratory environment, where the attenuation of uni-directional (and, if feasible, bi-directional) currents will be recorded through a series (e.g. Spartina alterniflora and Atriplex portulacoides) of mono-specific salt-marsh canopies. For each species, the vegetation density and height will be varied between individual experiments and the spatial structure of the canopy will be recorded each time using side-on digital photography of a 30-100 cm wide section of the canopy (giving an effective sampling interval of the order of 0.1 mm) and near-vertical ground-based LiDAR of the entire canopy with an average point-spacing of approximately 5 cm. Variations in canopy height as well as canopy density or 'porosity' metrics will be analysed using a series of statistical approaches, including an investigation of possible self-affine ('fractal') patterns common to natural surfaces (i.e. evidence of a power-law dependancy of the Fourier transform of the spatial measurement (e.g. the canopy height profile)). Such methods have, e.g., successfully been used to characterise the aerodynamic roughness elements of glacier surfaces (Rees and Arnold, 2006). The statistical relationship between the various 'roughness' and 'porosity' metrics on the one hand, and the degree of flow attenuation on the other hand, will then be investigated, with the aim of identifying which metric can most reliably be used as an indication of hydrodynamic roughness of the canopy.

The project is an agreed collaboration between CCRU and HR Wallingford Ltd and will be accompanied by a CASE award to the student. Whilst the student will be based in Cambridge, s/he will spend some research time at HR Wallingford Ltd, working alongside staff there.

C4. Decadal-scale morphodynamics of cohesive intertidal open coasts

Supervisors: I. Möller & T. Spencer

The behaviour of cohesive intertidal shores, characterised, in NW Europe, by mudflat and saltmarsh environments, is governed largely by the physical drivers of sea level, wave energy level, and sediment supply. While all three of these factors are expected to change as a result of longer-term (50-100 year scale) climatic changes (IPCC, 2007), the annual to decadal scale variability within these controls is likely to result in morphological changes of the intertidal zone over similar time-scales (see e.g. Allen (2000)). Moreover, it is likely, that the response of the intertidal zone to these physical stimuli is highly non-linear, controlled by thresholds, and characterised by morphodynamic feedback and lag-times.

This project aims to make use of extensive morphological and hydrodynamic datasets for a series of open coast or outer estuarine saltmarsh sites on the East coast of the UK (including The Wash (Lincolnshire), Wells/Stiffkey (North Norfolk), Dengie (Essex), and Medway (Kent)) to statistically evaluate the relationship between these physical drivers and the morphological response of the saltmarsh-mudflat interface. Morphological data will consist of cross-shore intertidal profiles and 1:5,000 aerial photographs held by the UK Environment Agency and available at annual intervals for the period 1991/2 to present (i.e. at least the last 16 years). Hydrodynamic datasets will be gathered from a range of sources, including hindcast model outputs of wave / water levels and water level records held at the Environment Agency and the British Oceanographic Data Centre. A series of statistical approaches will be used to investigate a range of possible non-linear statistical relationships between hydrodynamic forcing and morphological response with the aim of building a stochastic model to simulate horizontal erosion/accretion 'behaviour' of intertidal open coast wetlands on the UK East Coast.

D. Hydrology and fluvial processes - www.geog.cam.ac.uk/research/ep/hfp/

D1. Discrete element modelling of sediment transport systems

Supervisors: Keith Richards, Mike Bithell & Dongfang Liang (Engineering)

Discrete element methods are proving to be an invaluable means of understanding a range of particle interaction processes. They are well-developed in certain fields (eg, chemical engineering, powder technology), but their potential has yet to be fully exploited in environmental sciences. The aim of this project will be to develop such an application, with reference to one of a number of phenomena (bedload transport in rivers, scree sorting processes, long-runout debris avalanches). For example, classic examples of long runout landslides (eg, Franks, Blackhawk, Ulm) could be re-assessed, by reconstructing the pre-failure topography and the failed mass, and seeking to replicate the long runout behaviour of the slide debris. This will give insights into the rheology, and permit improvements to be made simplified macro-scale models of the process. A particular focus of this research is thus to extract key patterns of larger-scale behaviour from these micro-scale models, such as the distribution of shear, the potential for particle wear, the depositional characteristics and the effects of topographic features (and of structural protection measures). The project will employ a combination of terrain modelling and remote sensing to construct the topography, and scaled laboratory modelling and field monitoring in order to parameterize and test the models developed. It will be of interest to students with backgrounds in engineering, earth science, computing, applied mathematics and physical geography.

D2. Interactions of hydrology, vegetation and land use

Supervisors: Mike Bithell & Keith Richards

Temporal fluctuations in rainfall, on timescales from annual through to decadal and longer, change the spatial distribution of ground water availability, mediated by the soil-type, slope and landcover. This in turn determines the locations within the landscape that can support agriculture. Interception of rainfall and its infiltration into and movement through the soil is dependent both on vegetation and land-use - natural forest, actively harvested forest and farmland all have differing hydrological characteristics. The resulting soil moisture distribution and runoff rates affect soil erodibility and landslide probabilities, irrigation possibilities and rain-fed crop yields, flood frequency and stream discharge. New techniques in computational modelling now allow us to build models that represent some of the complexity of human behaviour and social interaction, and to couple these to ecological and physical models. This project will build on an existing environmental model that incorporates an agent-based model of a farming community, an individual-based forest model and spatially distributed hydrological model to investigate interplay between human decision-making, land-use change, vegetation dynamics and hydrology. In this way we can study the implications for biodiversity and the sustainability of various farming practices at the catchment scale. This inter-disciplinary project will be of interest to students with backgrounds in land use change, ecology or hydrology, or interests in interface between social and environmental systems. A grounding in applied mathematics, GIS or numerical computation would also be an advantage.

D3. Discrete element modelling of scree slope development

Supervisors: Mike Bithell & Keith Richards

Discrete element modelling is a computational technique that simulates the dynamics of particle assemblages by computing explicitly the trajectory of every particle under the forces of gravity and the effects of collisions with other particles or with solid surfaces. It is proving to be an invaluable means of understanding a range of particle interaction processes. It is well-developed in certain fields (e.g. chemical engineering, powder technology), but the potential has yet to be fully exploited in environmental sciences. The aim of this project will be to develop such an application, with reference to one of a number of scree sorting processes. The development of a scree may take place through infrequent falls of individual particles through to large scale multiple rock-fall events. The shape of the resulting slope is thought to be a result of the combination of large scale factors such as cliff retreat, energy of supply of the falling rocks, local slope characteristics and rate of removal of the resulting scree material, and individual particle properties such as size range, shape, surface friction and internal dissipation. The project will employ a combination of terrain modelling and remote sensing to construct the topography, and scaled laboratory modelling and field monitoring in order to parameterize and test the models developed.

D4. Modelling channel, floodplain and floodplain ecosystem dynamics

Supervisors: Keith Richards & Mike Bithell

Reduced complexity models (in which the hydrodynamics are treated in a simplified manner) are of increasing value in simulating longer-term evolution of fluvial systems at larger length scales (101-103 years, 103-106 metres). In particular, they have the potential to simulate evolution where significant change occurs in the boundary conditions for the flow, and therefore strong feedbacks occur amongst flow, sediment transport and topographic change. They could also allow interactions of hydrological, geomorphological and ecological dynamics to be studied, and therefore could be useful tools in the management of river-floodplain systems. Nevertheless, the potential is not easy to realize, because is it not always clear that the simplifications adopted allow realistic coupling of sub-models (eg of flow and sediment transport). The Department has a long term research programme to apply this class of models to floodplain dynamics, and projects have thus far explored flow models, simplified transport models, and simple models for ecological change. There remains scope for a variety of contributions to this programme, for example in coupling flow and sediment transport to derive predictions of channel change, in developing a model structure that allows simulation of channel pattern and defines the conditions when meandering or braiding occur, and in individual-based modelling of floodplain ecosystem structure and it feedback to the physical processes of flow and sediment transport. These projects would suit individuals with a variety of backgrounds, with experience in numerical modelling, computation and GIS and remote sensing being particularly relevant.

E. Atmospheric Processes - www.geog.cam.ac.uk/research/ep/ap/

E1. Implementation and Testing of a Convective Cloud Field Model for use in Global Climate Models

Supervisors: Prof. Hans-F Graf and Dr. Michael Herzog

Convective clouds are a challenging problem in atmospheric modelling at the scale of global climate models since they have spatial scales that cannot explicitly be resolved. In most cases the current parameterisations reduce the cloud spectra to a single mean cloud. This produces problems not only for the simulation of precipitation, but also for convective transport and latent heat release. While it is possible to parameterise these cloud spectra by cloud resolving sub-models, this is computationally by far too expensive for long climate simulations. The aim of this project is to implement a new Convective Cloud Field Model (CCFM) into a climate model after rigorous testing against observations and cloud resolving models, optimisation with respect to microphysics and initialisation, and adaptation. The use of CCFM allows to explicitly simulating cloud spectra without prescribing the spectrum properties from observations or cloud resolving models. It results also in explicit convective transport, microphysics inclusive the fate of soluble and non-soluble species and the effects of aerosols on cloud properties. The work will concentrate on i) a climate control run with CCFM which will be evaluated against the standard climate model and observations, both satellite and ground based, ii) a GCM simulation of the effects of different aerosols on convective clouds and climate, iii) implementing a convection transport scheme for atmospheric tracers and iv) providing a tested module for the parameterisation of convective cloud fields for use in climate models. Good mathematical/physical training is essential.

E2. Comparison of deep convection in single column and cloud resolving model using observed and idealized cases

Supervisors: Dr. Michael Herzog and Prof. Hans-F. Graf

Convection and its parameterisation are a major challenge in climate research. A recently developed convective cloud field model CCFM used in exchange of bulk mass flux schemes in climate models will be tested against the really cloud resolving model ATHAM and observations. It will be necessary to further develop a module of surface energy fluxes (soil model) for ATHAM. Extensive numerical simulations will be performed on the Darwin Supercomputer and the results be evaluated against campaign observations. The project will focus on process oriented research. Good mathematical/physical training is essential.

E3. Simulating co-ignimbrite eruptions with the plume model ATHAM

Supervisors: Dr. Michael Herzog, Prof. Hans-F. Graf and Dr. Clive Oppenheimer

Big explosive volcanic eruptions of the caldera forming type very probably are characterized by the formation of secondary eruption columns, the co-ignimbrite plumes. Explosive volcanic eruptions form buoyant plumes after sufficient entrainment has taken place. If a (buoyant) Plinian eruption plume cannot be formed, the eruption column will collapse. A secondary, so called co-ignimbrite plume can be formed from the developing pyroclastic flow. In previous work the behaviour of such co-ignimbrite eruptions has been studied by one-dimensional plume models based on the assumption that they can be regarded point sources. So far we used the three-dimensional plume model ATHAM in an idealized setup to investigate the impact of this assumption on the plume development. Clearly, Neutral Buoyancy Heights are overestimated when one-dimensional stationary top hat models are applied. Entrainment and wind shear have strong influence on the plume development. Co-ignimbrite plumes can be realistically represented only in a fully three dimensional model. The goal of the project is a more realistic representation of pyroclastic flows and the formation of the co-ignimbrite plume in the model ATHAM. The project includes some model development: implementation of terrain following coordinate system and a simple soil model. The results will be of theoretical nature and be based on comparing forcing and effects from idealized to more realistic configurations of the model. Specific observed cases will be simulated and evaluated. The sedimentation of ashes will be in the centre of the investigation and an intense evaluation of the classical sedimentation theory. ATHAM results and surface observations will be compared. Good mathematical/physical training is essential.

E4. Simulating radar signals for volcanic clouds: the ATHAM Radar Simulator

Supervisors: Dr. Michael Herzog and Prof. Hans-F. Graf

Volcanic eruptions pose a danger for aviation as ashes in the plume may destroy the turbines of jet engines, acids may destroy seals and ash may scratch windshields making them opaque. At several places, like in Sicily, Radar observations are used to monitor volcanic plumes but due to their changing nature the Radar signals are not easy to interpret. Hence, a first guess Radar signal is necessary that includes the varying composition of the plume. In collaboration with the University of l'Aquila, Italy, a module will be developed for the high resolution plume model ATHAM that allows simulating the RADAR reflectivity of a volcanic plume. Extensive comparison will be made against real observations. The module will further be developed into one that allows simulating the Radar signals of deep convective clouds. Good mathematical/physical training is essential.

E5. Stratospheric sulphur chemistry for volcanic injections

Supervisors: Prof. Hans-F. Graf and Dr. Michael Herzog (collaboration with Prof. John Pyle, Chemistry)

Volcanic eruptions, large wild fires and deep convective clouds can inject large mounts of solid material, tropospheric trace gases and ice into the lower stratosphere. While the very high resolving model ATHAM can simulate this injection, its time frame is too short to also simulate the fate of this material in the stratosphere. The PhD work will consist of simulations with ATHAM for a number of typical weather conditions of the stratospheric injection of SO2, water vapour and ice particles. These injected masses will then further be treated in a Chemistry-transport model TOMCAT (available at the Chemistry department) to simulate their fate over several days. This will, for the first time, allow to estimate the effective amount of direct stratospheric injection of tropospheric material into the stratosphere. Results will be evaluated against in situ and satellite observations. Good mathematical/physical training is essential.

F. Volcanology

F1. Lava lake dynamics

Supervisors: Clive Oppenheimer, Philip Kyle (New Mexico Tech.), Bruno Scaillet & Alain Burgisser (CNRS, Orléans)

Lava lakes provide windows into the magma networks that feed active volcanoes. Their observation can provide important insights into magma transport and eruptive styles. A few lava lakes, including those hosted by Mt. Erebus (Antarctica), Erta 'Ale (Ethiopia) and Nyiragongo (D.R. Congo), have been continuously active for decades. Such persistence suggests bidirectional magma flow in the feeder conduit, driven by density contrasts arising from degassing. However, few observations distinguish the manner in which gases separate from magmas, undermining efforts to evaluate physical models for magma rheology and eruptive behaviour.

The aim of this project is to advance linked physical and chemical models of lava lakes and their deeper plumbing systems and, in effect, to provide a detailed "image" of key subsurface processes taking place beneath active volcanoes. It is expected that the project will entail fieldwork at Mt. Erebus to include detailed observations of gas and heat emissions, combined with periods of laboratory analysis and experimental work to determine petrological parameters needed to improve and constrain dynamical models for magma and gas transport.

The ideal candidate will be highly numerate and have a background in or, at least, a strong penchant for more than one of the following fields: volcanology, analytical and/or experimental petrology, geophysical fluid dynamics, atmospheric spectroscopy. Further training will be provided in aspects of all these fields as required. The anticipated fieldwork is physically demanding and periods of several months of labwork including experimental design and analysis are likely.

References (all available on request – contact Clive Oppenheimer)

F2. Atmospheric chemistry of tropospheric volcanic plumes

Supervisors: Clive Oppenheimer, Rod Jones (Department of Chemistry), Robert Martin (Department of Earth Sciences) & Philip Kyle (New Mexico Tech.)

An important finding that has emerged from studies of the geochemical budgets associated with global volcanism is the disproportionate contribution of sulfur emissions from non-explosive, degassing volcanoes relative to other sulfur sources, including anthropogenic and oceanic emissions (e.g., Graf et al., 1997). This reflects, in part, the altitude of the volcanic source, a characteristic which typically leads to enhanced residence times for volcanic emitted sulfur gases and aerosols. Thus, the temporal and spatial variability in this "background" volcanic source may represent an important climate forcing factor that has yet to be fully characterised. In addition to the impacts from sulfur compounds, there is further evidence of enhanced atmospheric chemical reactivity induced by volcanic plumes due to the presences of reactive halogens (e.g., Oppenheimer et al., 2006) and nitrogen species (e.g., Oppenheimer et al., 2005). In light of these findings, it is likely that, at least on a local scale, volcanogenic halogens strongly perturb tropospheric acidity and its oxidizing capacity (Roberts et al., 2009).

The aim of this project is to develop a firmer understanding of the oxidative effects of volcanic plumes through a combination of careful field observations and modelling. The modelling side will build on the recent construction of a model for volcanic plume chemistry described by Roberts et al. (2009), and involve exploration of more complex reactions between sulphur, halogen and nitrogen compounds. The field measurements will be designed to obtain key information on gas and aerosol composition of volcanic plumes, and the evolution of plume chemistry and aerosol properties as the volcanic cloud drifts downwind. It is anticipated that fieldwork will be conducted at Mt. Erebus (Antarctica) and likely one or more other volcanoes (e.g., Mt. Etna, Italy, and Masaya volcano, Nicaragua).

The ideal candidate will be highly numerate and have a background and keen interest in more than one of the following fields: atmospheric chemistry / modelling, absorption spectroscopy and/or aerosol lidar observation and analysis, radiative transfer theory, volcanology. Further training will be provided in aspects of all these fields as required. The anticipated fieldwork is physically demanding substantial effort will go into data analysis and interpretation and development of computational modeling tools.

References (all available on request – contact Clive Oppenheimer)

F3. Quaternary volcanic geology and geoarchaeology of Yemen

Supervisors: Clive Oppenheimer, Lamya Khalidi (Université de Nice), David Pyle (University of Oxford)

Much of Yemen is geologically related to the continental break-up of the Afro-Arabian province and opening of the Red Sea. The Plateau shares much in common with the series of Oligocene volcanic series (mostly flood basalts but with significant volumes of rhyolite) in Ethiopia. There has been recent excellent work carried out on these deposits on both sides of the Red Sea. However, there is also a substantial record of Quaternary volcanism in Yemen, with the most recent eruption that on Jebel al Tair island in 2007-8. This record has been much less explored.

Following a reconnaissance field mission in 2008, we have identified the Harras of Dhamar (a few hours drive south from the capital Sana'a) as a particularly fruitful region for modern volcanological work. The aim of the project will be to build a picture of volcanic history of the area, focusing on the Holocene and Recent products of Jebel Lisi and Jebel Isbil volcanoes. We have one radiocarbon date for pyroclastic deposits that identifies an eruption in the last few thousands of years. Thus we are keen to explore also the consequences of these eruptions for human populations living in the region whose evidence is clear from a rich archaeological record. For instance, obsidian lavas were widely used as a resource during the middle Holocene and an important question concerns the provenance of the raw materials used to make the artifacts that abound in the archaeological record. The project will entail one or more field seasons devoted to careful mapping and sample collection, followed by extensive petrological, geochemical and geochronological analysis of rock suites obtained.

The ideal candidate will have a strong background in igneous petrology / volcanology, and an interest in geoarchaeology. Fieldwork in Yemen will be subject to careful reviews of security and cannot be guaranteed. In the event of difficulties in working in the country, the focus of the project could switch to the other side of the Red Sea (i.e., Ethiopia or Eritrea). Interacting with people living in the tribal areas of Yemen demands especial sensitivity and cultural understanding.

References

G. Landscape Ecology

G1 : Integrating field-surveys with airborne remote sensing for the monitoring of biodiversity in Mediterranean evergreen shrubland ecosystems

Supervisors: Dr Harriet Allen and Dr Bernard Devereux

The aim of this project is to devise protocols which will lead to the integration of field survey data for LiDAR-derived parameters for the characterisation of Mediterranean evergreen shrubland vegetation communities. In the last 50 years, land-use practices associated with urbanisation and agriculture have resulted in considerable fragmentation and loss of habitat in these ecosystems. Such landscape modification is of international concern for conservation given that the Mediterranean region is one of the most biodiverse in Europe. Monitoring the degree and consequences of such landscape change involves scaling high resolution field-based data, to the broader scale of remotely sensed data and examining the degree to which airborne imagery, such as LiDAR, can be used to derive surrogate measures of biodiversity .

The use of LiDAR for modelling vegetation canopy and structure is a growing area of research interest but challenges exist in its use for characterising biodiversity in landscapes with high topographic and vegetation community diversity, such as many of those in the Mediterranean region. It is intended that the main geographical area of interest will be the evergreen shrubland communities of the Psiloritis region in central Crete from which LiDAR data has already been collected and where the Department has long-standing research interests. However, there may also be possibilities for extending the geographical scope of the project to other areas of the Mediterranean.

As part of this project full training will be given in the acquisition and analysis of LiDAR data and other remote sensing imagery and well as field-training in the acquisition of relevant ecological and environmental data from the areas of interest.