PhD projects
It would be helpful if you could indicate in your application form which PhD topics interest you and also put your choices in approximate order of interest. Such a choice does not exclude you from choosing another topic, or from suggesting a topic of your own, when you visit the Department for an interview on our Visit Day on Wednesday 10 March). You may wish to see our staff research interests.
Note that these projects, unless otherwise stated, normally only provide full funding for UK students or residents (see funding for more details). Prospective students who are able to secure their own funding are not bounded by the list of topics offered here. You may wish to see our staff research interests and contact the Postgraduate Admissions Tutor, Dr Robin Hogan on how to proceed.
- Application forms can be downloaded here (this is preferable to the online form)
- Please note the checklist on the application form
- Additionally include a transcipt of subjects taken for your degree and marks achieved
- Note that for our PhD Programme we do not require a project description
- Apply before the beginning of March to ensure an invitation to our visit day
- We will not consider unsollicited CVs sent via email; you must fill in an application form
- The expected start date is October 2010, but please let us know as soon as possible if you are able to start before summer 2010, as we still have two NERC studentships to be filled in the current academic year.
List of topics
Updated February 2010
- Simulating changes in glacier mass balance and their impacts on hydrological regimes across the globe (Professor Nigel Arnell)
- The dependence of urban climate on building layout and design (Dr Janet Barlow)
- Assessing the validity and impact of urban scale numerical weather prediction (Dr Janet Barlow and Professor Peter Clark)
- Determining the turbulent structure of the urban atmosphere (Dr Janet Barlow)
- The effect of urban climate on urban energy supply and demand (Dr Janet Barlow)
- Modelling London's urban climate (Professor Stephen Belcher)
- Costs and benefits of geo-engineering in the stratosphere (Dr Andrew Charlton-Perez and Dr Eleanor Highwood)
- Very-high resolution global atmospheric modelling experiments to understand gravity-wave processes in the middle atmosphere (Dr Andrew Charlton-Perez, Professor Lesley Gray, Dr David Jackson and Dr Neal Butchart)
- The Science and Law of Climate Change: Interdisciplinary PhD Studentship (Dr Andrew Charlton-Perez and Dr L. McNamara (Law))
- Inferring cloud optical properties from ground-based radiation measurements (Dr Christine Chiu and Dr Robin Hogan)
- Cloud edges: Understanding aerosol and cloud properties from radiation measurements and model simulations (Dr Christine Chiu and Dr Robin Hogan)
- The predictability of sudden stratospheric warmings (Professor Lesley Gray)
- Snow observations and modelling (Professor Robert Gurney) TAKEN
- Comparison of atmospheric turbulence observations by weather balloons with model predictions (Professor Giles Harrison and Dr Paul Williams)
- Storm tracks and clmate change (Dr Kevin Hodges)
- Convective heating profiles in the tropics and their relationship to errors in climate models (Dr Pete Inness and Dr Steve Woolnough)
- Anchoring of convective storms (Dr Daniel Kirshbaum and Dr Bob Plant)
- The origin of the water in weather systems leading to UK flooding events (Dr John Methven and Dr Mike Blackburn)
- Galactic cosmic rays, the Sun's magnetic field and climate change (Dr Mathew Owens and Professor Michael Lockwood)
- Self-organized criticality in tropical convection (Dr Bob Plant)
- The moisture cycle in mid-latitude weather systems in a changing climate (Dr Bob Plant and Professor Stephen Belcher)
- Application of thermodynamic optimization theory to the prediction of tropical-cyclone intensity (Dr Remi Tailleux and Dr Sue Gray)
- Ensemble data assimilation in tropical cyclone risk modelling (Professor Peter Jan van Leeuwen)
- Dynamically simulated tropical storms in a changing climate and their impact on the assessment of future climate risk (Professor Pier Luigi Vidale, Dr Kevin Hodges, Dr Jane Strachan and Matt Foote)
- Effective atmospheric modelling for space geodesy (Professor Geoffrey Wadge)
- Novel mixing schemes in ocean models (Dr Paul Williams and Professor Jonathan Gregory)
- How do jet stream changes affect the propagation of Rossby waves? (Dr Tim Woollings)
Project descriptions
Simulating changes in glacier mass balance and their impacts on hydrological regimes across the globe
Professor Nigel Arnell
Mountain glaciers and small ice caps make important contributions to both hydrological regimes and water resources at the local and regional scale, and are potentially very sensitive to climate change. The overall aim of this project is to examine the implications of changes in glacier melt for hydrological regimes and water resources across the global domain. The specific objectives are to develop a generalised glacier mass balance model (capable of application with appropriate input data across the global domain), integrate this model into an established global-scale hydrological model, and use the coupled glacier-hydrology model to estimate the impacts of defined climate change scenarios on hydrological regimes and water resources at local, watershed, regional and global scales.
The dependence of urban climate on building layout and design
Dr Janet Barlow
Detailed project description (PDF)
Over 50% of the world's population now lives in urban areas. As cities grow they develop their own, distinct microclimates - for instance, in many areas an Urban Heat Island is observed, whereby the city is several degrees warmer than the surrounding countryside. Overheating already affects many urban citizens during heatwaves, which are forecast to be much more frequent by mid-century. The degree of warming depends upon how heat is exchanged between the urban surface and the atmosphere, which in turn is governed by the complex flow patterns that develop around buildings. The aim of this project is to investigate the dependence of urban flow and heat exchange on the layout and design of buildings. The student will use state-of-the-art wind tunnel simulations of both idealised and realistic building layouts to develop understanding and parameterisations of heat exchange. As the results will impact on simulations of both indoor and outdoor climate in urban areas, it is anticipated that the student will interact strongly with engineering consultancy firm Arup, with whom a CASE award is anticipated. An EPSRC studentship is already available for this project, which is part of the Advanced Climate Technology Urban Atmospheric Laboratory (ACTUAL) project (www.actual.ac.uk).
Assessing the validity and impact of urban scale numerical weather prediction
Dr Janet Barlow and Professor Peter Clark
Forecasting weather at the urban scale has become easier in recent years with increased model resolution, and more sophisticated representation of the urban surface. Numerical Weather Prediction data is also useful for modelling air quality, or even for urban planning and design purposes. But are the simulations actually capturing reality, in terms of exchanges of heat, moisture and energy with the atmosphere above? Over the complex urban surface, do the simple assumptions about atmospheric boundary layers that the models employ still apply? Answering these questions has been difficult, given the lack of high quality meteorological data in urban areas. Over the next few years, including the period of the 2012 Olympic Games, the ACTUAL project will be capturing high grade observations of the urban atmosphere. This project will investigate the validity of assumptions used in Numerical Weather Prediction models in simulating the urban boundary layer (heights up to 1-2km) which determines urban climate. Work will also include investigating the potential of using NWP data for a range of engineering applications including energy efficient urban design, wind engineering of tall buildings, and so on. It is anticipated that The Met Office will provide a CASE award for this project. An EPSRC studentship is already available, and the student will be part of the Advanced Climate Technology Urban Atmospheric Laboratory (ACTUAL) project team (www.actual.ac.uk).
Determining the turbulent structure of the urban atmosphere
Dr Janet Barlow
The turbulent nature of the urban atmosphere - or urban boundary layer (up to 1-2km in depth) - is governed by its response to a complex, rough surface - changes in surface cover cause patchiness in surface fluxes of heat and water vapour, and changes in building shape and layouts cause changes in drag and turbulence. The distribution of pollutants across a city or even the temperature experienced at the ground both depend on the boundary layer dynamics on both a daily and seasonal basis. The question is, are our models of the way the urban boundary layer behaves borne out by reality? Until now observations of boundary layer structure have been hard to come by: the technology of Doppler lidars has developed to the point where they can be easily deployed over long periods. This project will investigate the use of Doppler lidar in long term observations of the urban boundary layer in London. The student will gain hands-on experience with the instrument, and optimise the use of the instrument in measuring wind, turbulence and aerosol backscatter structure of the urban atmosphere. There will be opportunities to take part in large field campaigns involving scientists from across the UK as part of the ClearfLo and ACTUAL projects (Advanced Climate Technology Urban Atmospheric Laboratory, (www.actual.ac.uk).
The effect of urban climate on urban energy supply and demand
Dr Janet Barlow
Energy demand in urban areas is large due to the dense population. Urban climate can influence demand - milder winters in urban centres reduce heating needs, but hotter summers produce huge demand, particularly if air conditioning is required. Demand can be met partly through increased use of renewable energy and energy efficiency: indeed, new property developments in London are required to produce 10% of their energy through renewable means (the so-called "Merton rule"). So what is the potential of the urban climate in terms of renewable energy? And will use of natural ventilation to cool buildings efficiently function as well if buildings are more densely packed in urban centres? This project will address these and related questions through analysis of London's climate data and development of a modelling approach to simulate the impact of the urban climate on energy supply and demand in London, both now and into the future. The student will be part of the Advanced Climate Technology Urban Atmospheric Laboratory (ACTUAL) project team (www.actual.ac.uk).
Modelling London's urban climate
Professor Stephen Belcher
Cities, such as London, generate their own, local, climate. For example, London's night time temperatures can exceed the surrounding rural temperatures by more than 5K. Because so many of us live in cities, there is huge interest in understanding how the climate of cities will change in the future. Consequently, there is a strong desire, and scientific challenge, in developing methods for predicting this local climate and how it might change as cities grow and the global climate warms. Recently at Reading we have developed techniques to model local climates in cities, and the aim of this PhD is to use these techniques to establish the drivers for London's urban climate and then to quantify how London's climate might change in the future. The work will require a blend of fundamental theory and high-resolution numerical modelling using the Met Office numerical weather forecast model.
Costs and benefits of geo-engineering in the stratosphere
Dr Andrew Charlton-Perez and Dr Eleanor Highwood
Detailed project description (PDF)
Anthropogenic climate change is a major threat to food security and human health over the next century. Due to its large potential impacts several authors have proposed technological fixes to the problem which do not involve immediate large-scale decarbonisation. These approaches are collectively known as geo-engineering. One potential method of geo-engineering is to artificially replicate the cooling effect of large tropical volcanic eruptions by putting large amounts of sulphate aerosols into the stratosphere. In this project the student will investigate the impact of aerosol injection geo-engineering schemes on the dynamics and circulation of the stratosphere. This a major unknown in our current understanding of the impacts of stratospheric geo-engineering. It has added importance, because large changes to stratospheric circulation could have significant impacts on ozone depletion and recovery and on the tropospheric circulation. The student will use both simple climate models and a complex chemistry-aerosol-climate model to understand qualitatively and quantitatively the costs and benefits of large-scale geoengineering.
Very-high resolution GCM experiments to understand gravity-wave processes in the middle atmosphere
Dr Andrew Charlton-Perez, Professor Lesley Gray, Dr David Jackson (Met Office) and Dr Neal Butchart (Met Office)
Detailed project description (PDF)
Small-scale atmospheric buoyancy oscillations known as gravity-waves are ubiquitous in the atmosphere and can play an important part in the overall momentum budget. This is particularly true in the stratosphere and mesosphere where the structure and variability in the extra-tropics and tropics is strongly influenced by gravity-wave breaking. Models used to predict stratospheric and tropospheric climate generally have quite coarse horizontal resolution, larger than the scale of most important gravity waves (10-100km). This means that most models require additional statistical parameterization schemes to represent the influence of gravity-waves on climate. Unfortunately, observational constraints on the parameters used in the parameterization schemes are very weak and this uncertainty contributes to the overall uncertainty of climate models and their predictions. In this project, the student will be part of a new collaboration between the University of Reading and the Met Office which will attempt to improve our understanding of gravity waves in the troposphere and stratosphere. The student will be involved in analysing a long-simulation of a very-high resolution model (~25km) which can resolve many of the important gravity-wave motions. The student will gain experience in atmospheric dynamics and in the use of numerical models for weather and climate prediction. The aim of the analysis will be to understand how better to represent gravity-waves in models used to predict future climate and the future evolution of the ozone hole.
The Science and Law of Climate Change: Interdisciplinary PhD Studentship
Dr Andrew Charlton-Perez and Dr L. McNamara (Law)
Global climate is predicted to change markedly over the coming century. A large proportion of this projected change is due to changes to climate forcings caused by human activity. As the IPCC (2007) stated, it is very likely that observed increases in global temperature since the middle of the 20th century are the result of past anthropogenic emissions of greenhouse gases. These past and future global changes are likely to have profound impacts on societies around the globe, and to have disproportionate impacts in neighbouring regions. Although governments are increasingly aware of the need to both mitigate the impact of dangerous climate changes and adapt their societies to their harmful effects, such measures are likely to be very costly in pure economic terms. Of the many political, cultural and legal strategies that are being employed to change and regulate behaviour to meet these challenges, this project considers one of the most significant emerging strategies: litigation. In this project, the student will examine the ways in which the strategies used to detect and attribute climate changes can be applied within a legal framework. The project will be interdisciplinary and will require student to participate in novel climatological and legal scholarship. There is also a possibility that the project will attract CASE sponsorship from the Met Office.
Inferring cloud optical properties from ground-based radiation measurements
Dr Christine Chiu and Dr Robin Hogan
Cloud optical properties are a crucial determinant of the Earth's radiative energy balance. Future climate warming predictions can vary in a wide range just by changing the way we model cloud-radiation interactions. Yet we know remarkably little about clouds globally, in spite of over a decade of rapidly increasing numbers of measurements, and clouds continue to surprise us with new phenomena and new behaviors. Thus, we need a dramatic increase in the number, accuracy, and variety of cloud observations if we are to have any hope of representing clouds successfully in climate models. However, measuring clouds from the surface using traditional methods, as well as from satellites, has been challenging because clouds are complicated 3D quasi-fractal objects that evolve fast. This project aims to accurately infer cloud properties using radiation measurements that can catch clouds at the natural timescale of their evolution. The student will gain hands-on experience with radiation instruments and learn to use 3D radiative transfer models. The student will also develop/refine retrieval methods, and analyze data from ground-, aircraft- and satellite-based observations. This project will have broad impact, because methods developed here will find immediate application in existing and planned global observation networks.
Cloud edges: Understanding aerosol and cloud properties from radiation measurements and model simulations
Dr Christine Chiu and Dr Robin Hogan
The IPCC has recognized aerosol-cloud interactions as the largest source of uncertainty in climate radiative forcing. Meanwhile, clouds present the largest uncertainty among the numerous climate feedback processes. Where are the strongest aerosol-cloud interactions taking place, and where are these interactions most assessable? One answer is, near cloud edges, the transition zone between cloudy and cloud-free areas. This zone is a battleground where aerosols are struggling to become cloud drops at the same time as cloud drops are struggling to evaporate. Thus, this zone is a good place to study rapidly-evolving aspects of clouds and aerosols. The transition zone remains a kind of research no-man's land (both the aerosol and cloud retrieval community avoid this zone). This project aims to better understand the radiative signature of aerosol and cloud in the transition zone, and to invent new retrieval methods using ground-based radiation measurements. Results from this project will advance our understanding of physical processes near cloud edges, such as activation and evaporation of cloud droplets and humidification of aerosols. This project will also help improve and validate aerosol-cloud interaction parameterizations.
The predictability of sudden stratospheric warmings
Professor Lesley Gray
Sudden Stratospheric Warmings (SSWs) occur in the region ~20-50km above the Earth's surface, the layer often referred to as the Ozone Layer. In the Northern Hemisphere (NH) they occur roughly every other winter and are associated with vertically travelling planetary-scale waves. These waves are generated in the underlying troposphere, mainly by air flow over large mountain ranges and by land-sea contrasts, which are far more prevalent in the NH than in the Southern Hemisphere (SH). There has been only one recorded SSW in the SH. However - who knows what will happen in the future? Idealised model predictions have suggested that the characteristics and frequency of NH warmings will change as CO2 levels rise. The prime aim of this study is to improve our understanding of the mechanisms that trigger SSWs and which aspects of the climate system they are most sensitive to. We will use results from state-of-the-art climate model simulations that are currently being run by the Met Office Hadley Centre and elsewhere, to contribute to the next report of the Intergovernmental Panel on Climate Change (IPCC). For the first time, the model will be run with an upper lid at ~80km so that stratospheric processes can be well resolved, including SSWs. We will examine the modelled behaviour of SSWs and explore the reasons for changes in their characteristics, including tropospheric wave train patterns and how they are influenced by the background winds as they propagate vertically and influence the stratospheric polar vortex. Changes in the polar vortex during SSWs are known to influence the underlying weather and climate, and we will explore the impact of future SSW changes e.g. on the North Atlantic Oscillation, which impacts the weather in the UK and Europe. Simple experiments will be performed with the model, in which small perturbations are imposed to isolate and understand specific mechanisms. The project will interest a student with a strong physics or mathematics background.
Snow observations and modelling (TAKEN)
Professor Robert Gurney (Project based in ESSC)
Many of the studies of possible global warming show that the greatest warming will occur in polar regions. There are also considerable risks of positive feedbacks in a warming, because melting areas of permafrost could release methane in large quantities. Sea ice in the Arctic Ocean is already apparently reducing in area and thinning, although it is not yet certain whether this is part of a global warming. There have been observations of Northern hemisphere land snow area for nearly 50 years from spacecraft, and for nearly 30 years there have also been estimates of Northern hemisphere snow mass on land made from passive microwave observations. Both have some uncertainties, particularly in areas of dense vegetation. Recent advances in radiative transfer modelling may allow more understanding of retrievals of both snow area and snow mass, as well as of related variables related to snow structure. Recent work has also shown that there are significant differences between observations and climate model outputs, particularly on snow mass distribution, which need to be resolved if there is to be confidence in model predictions. This student will examine the use of spectral data on snow reflectance, and how these can be used to infer snow properties and their change over a season. They will also use a model of a snowpack, and help with its further development, that will predict the change in snow properties over time. Coupling this with a suitable model of snow reflectance, the student will check that the model predictions of snow spectral properties over time agree with observations. The student will also incorporate a model of vegetation radiation interception that has already been tested, to examine the effects of vegetation on the observations. Colleagues in ESSC will couple the same model to a microwave emission model, so that joint use of optical and microwave remote sensing data can be examined. Initial data used will come from existing field data taken in Idaho and Colorado, but there are opportunities to collect further field data as necessary, in Idaho, Canada and elsewhere. There are new and exciting ways of observing snow structure using Ground Penetrating Radar and similar techniques, and there will probably be opportunities to collaborate with scientists making these novel observations. If the retrieval techniques are successful, there may be opportunities to implement them with global remote sensing data held in NASA, Canada and elsewhere.
Comparison of atmospheric turbulence observations by weather balloons with model predictions
Professor Giles Harrison and Dr Paul Williams
Atmospheric turbulence is a common and important feature of the terrestrial atmosphere, but in severe weather it can present a highly dangerous hazard to aircraft. Turbulence is potentially predictable using numerical atmospheric models, by applying various diagnostics to identify the destabilised regions that are most susceptible to turbulence. A new sensor has been developed recently at Reading to detect the turbulence encountered during routine weather balloon flights, which, by the use of GPS position information, can also determine the time and location of the turbulence. A series of flights have been made using this sensor. New turbulence diagnostics have also been developed recently at Reading. This project will compare the positions of turbulence measured by the new sensor with regions of turbulence predicted by numerical models, in order to test and refine the models. Further, theoretical understanding of the weather balloon's response to atmospheric turbulence will be used to inform subsequent sensor developments.
Storm tracks and climate change
Dr Kevin Hodges (Project based in ESSC)
The climate model simulations in support of the IPCC 5th Assessment Report are currently in production. These will include simulations from nearly 20 groups for two main temporal scales; decadal at high resolution to simulate the next 25 years and centennial at lower resolutions to simulate from the pre-industrial until 2100 and beyond. The simulations will make use of the very latest coupled climate models and new emission stabilization (mitigation) scenarios. Data from these simulations will constitute the CMIP5 data archive. For the first time the CMIP archive will include high frequency atmospheric output which will allow both tropical and extra-tropical cyclones to be identified and their distribution and properties studied using a sophisticated analysis system that identifies the storms and tracks them. Whilst individual model studies of these storms have been studied in the past, the new CMIP5 archive will provide an unprecedented opportunity to study these storms and the likely changes in them in a warmer climate and to compare between the different models. In addition, the realism of the models will be determined by contrasting them with new high resolution reanalyses that simulate the past 50-100 years using modern NWP methods. In parallel with CMIP5, paleoclimate coupled models will also be run to produce the PMIP3 archive. The simulations that will be performed will be pre-industrial control, mid-Holocene, last glacial maximum, last millennium, last interglacial and Pliocene. These also will also archive high frequency data for limited periods that will allow storms and storm tracks to be studied. The very different climates simulated by the paleo-models will allow a better understanding of the mechanisms that control the properties of storms to be determined.
Convective heating profiles in the tropics and their relationship to errors in climate models
Dr Pete Inness and Dr Steve Woolnough
In the tropical atmosphere, the large scale circulation of winds and the location of deep convective precipitation are intimately linked. The latent heat released in deep convective clouds provides the energy source for the wind circulation, and the winds in turn provide the mositure source for the convective precipitation. The current generation of Numerical Climate Models exhibits many errors in the location of the heaviest rainfall in the tropics, and in the variability of that rainfall. Many of these errors may be related to the vertical distribution of latent heat release within deep convective clouds. Several studies have shown that the vertical distribution of the latent heat release can profoundly affect the horizontal wind circulations that develop in response to the heating. In this project we will use climate models of varying complexity, together with a wealth of observational datasets, to analyse the effects of the vertical distribution of convective heating on systematic errors in tropical circulation patterns and rainfall distributions in climate models.
Anchoring of convective storms
Dr Daniel Kirshbaum and Dr Bob Plant
Detailed project description (PDF)
If a convective storm is sustained over the same location for several hours, then flash-flooding can result, posing serious hazards to life and property. While the basic ingredients for convective storms (instability, moisture, and lifting) are well known, the physical mechanisms that anchor storms to specific locations are less obvious. In some cases the storms are rooted to a local topographic feature such as a mountain or the coastline, while in other cases stationarity results from a complex interaction between the storm outflow and its surrounding environment. In this project, we will analyze the mechanisms behind, and predictability of, quasi-stationary convection in the UK, using a combination of observations, modelling, and theory. Observations are needed to identify and understand recent events. Model simulations (using state-of-the-art weather forecasting models) are needed to isolate the key physical mechanisms, and to assess predictability through the sensitivity to small changes in initial conditions and model physics. Simple theoretical models capturing the key processes are the end goal, and are needed to provide quantitative guidance to aid operational forecasting of these events.
The origin of the water in weather systems leading to UK flooding events
Dr John Methven and Dr Mike Blackburn
Detailed project description (PDF)
It has been suggested that the UK will experience more frequent high rainfall events as climate warms. Part of the reasoning is that warmer air has a higher saturation vapour pressure and therefore, all else being equal, rising air will be carrying more water to rain out. Observations do show increasing rainfall intensity over the UK in recent decades, but we cannot say whether this is related to climate change. One reason is that the relationship between rainfall and weather systems is highly variable and not nearly as simple as the argument above. The second is that changes in atmospheric circulation, including the frequency and intensity of storms, also affect rainfall rates and total accumulations. For example, the exceptional rainfall of summer 2007 resulted from 3 cyclones stalling over the UK. The moisture-laden "warm conveyor belt" airstreams of each storm originated from near the Azores where sea surface temperatures were cooler, not warmer, than average. In this project we propose using a novel technique to identify the contributory factors in recent UK precipitation variations and trends, focusing on the origin of moisture-laden air brought to the UK by storms. You will use a computer model driven by meteorological analysis data to build an air-mass trajectory climatology and analyse it to investigate whether the origins and water-loading of air in recent extreme seasons such as summer 2007 were atypical, and whether there have been any significant changes in these properties over recent decades.
Galactic cosmic rays, the Sun's magnetic field and climate change
Dr Mathew Owens and Professor Michael Lockwood
Galactic cosmic rays (GCRs) are extremely high energy particles which originate far outside our solar system and travel at almost the speed of light. The effects of these particles, and of the cascade of secondary particles that they produce in Earth's atmosphere, have a number of known and postulated effects on Earth's atmosphere, surface and lifeforms. The GCR flux incident on Earth's atmosphere can be measured using space- or ground-based monitors. Such observations have shown that the Sun's magnetic field (in what is termed the heliosphere) partially shields the inner solar system from energetic particles, allowing GCRs to be used as proxies for the solar magnetic field strength - and hence the Sun's brightness - when direct measurements are not available. Prehistoric GCR fluxes are inferred from isotopic depositions in reservoirs such as ice cores, ocean sediments and tree trunks and are used in reconstruction of solar irradiance thousands of years in the past, vital for quantifying the role of solar variability in terrestrial climate change on centennial and millennial timescales. However, the justification of the use of these proxies is somewhat superficial and detailed studies of the heliospheric structure, how it shields Earth from GCRs, and how it relates to the changes in the solar photosphere are required. The student will undertake analysis and modelling of spacecraft and ground-based data to relate GCR shielding to solar magnetic activity and heliospheric structures, with an eventual goal of improving reconstruction of Sun's irradiance for use in climate modelling.
Self-organized criticality in tropical convection
Dr Bob Plant
Detailed project description (PDF)
The weather and climate of the tropics is dominated by convective clouds. Recent observational analyses have provided evidence that tropical convection appears to share many features of self-organized criticality (SOC). SOC is a concept from statistical physics that describes some interacting systems of many degrees of freedom. In SOC systems internal interactions can drive the system towards a critical state, characterised by large variability over a wide range of space or timescales. Examples of systems which have been effectively described using SOC include avalanches, earthquakes and (more controversially) biological evolution. But we simply do not know what the important interaction mechanisms are between convective clouds that might produce SOC behaviour. The PhD will consider various possible interaction mechanisms, and use these to inspire various simple, phenomenological models for tropical convection. The aim is to determine the role of cloud-cloud interactions in observed organization, and so to try to identify the physical mechanism for SOC.
The moisture cycle in mid-latitude weather systems in a changing climate
Dr Bob Plant and Professor Stephen Belcher
Detailed project description (PDF)
There are huge scientific challenges in understanding the global, atmospheric, moisture cycle and how it might change as the climate changes. Frontal mid-latitude weather systems play a key role in cycling moisture in the atmosphere: they transport moisture from the sub-tropics towards the poles and also from near the surface to higher altitudes. Much, but not all, of the cycled moisture is rained out of the atmosphere by these weather systems. Recent research at Reading has shown how this cycling works in an idealised setting. The first goal of this PhD is to examine how the cycling works in the real atmosphere by analysing long-term simulations from high-resolution numerical models. The second goal of the PhD is to determine the factors that control changes to this cycling as the atmosphere warms in a changing climate.
Application of thermodynamic optimization theory to the prediction of tropical-cyclone intensity
Dr Remi Tailleux and Dr Sue Gray
Detailed project description (PDF)
Tropical cyclones (TC) constitute one of the most frightening extreme weather phenomenon known to mankind, which makes it one of the most fascinating topics of inquiry in meteorology. One of the most successful and popular theory for TC is Kerry Emanuel's Potential Intensity Theory, which predicts the maximum intensity achievable by a TC for known values of the environmental parameters. Physically, this theory regards TCs as mechanically-dissipated Carnot heat engines drawing their energy from air-sea enthalpy fluxes. Comparison with observations reveals, however, that the potential intensities predicted by Emanuel's theory usually far exceed observed TC intensities. The discrepancy strongly suggests that irreversible effects need to be accounted for in order to achieve predictions of TC intensities closer to observed ones. The aim of this project will be to include such thermodynamic irreversibilities in Emanuel's theory, in order to improve the latter. This goal will be achieved by making use of exciting new developments in the field of thermodynamic optimization achieved over the past three decades in the thermodynamic engineering community.
Ensemble data assimilation in tropical cyclone risk modelling
Professor Peter Jan van Leeuwen
Catastrophe risk models are used by insurance and investment companies to assess financial risk due to severe events such as land-falling hurricanes. The main objective of this project is the reconstruction of overland wind fields for actual land-falling hurricanes and typhoons from past archives, for up to 1 km resolution. These reconstructions are used to calibrate and validate a catastrophe model. As well, in real time, such reconstructions can be used to drive real-time insured loss modeling. Real-time loss modeling is crucial to the operations for a variety of companies who take financial risks on assets vulnerable to such storms. The proposed project involves investigating the use of ensemble data assimilation technology to improve reconstructions of historical land- falling hurricane events, using the kind of track and wind models adopted by catastrophe models for high resolution simulation of wind fields. We start with relatively simple experiments with simulated observations, to learn which ensemble data-assimilation methods work best. Using the DART software package the experiments will be made more complex, learning from previous experience. The best method(s) are then applied to real observations of past hurricanes to generate the benchmark for the catastrophe models. The work will be performed in cooperation with Risk Management Solutions, which is the leading developer and provider of catastrophe risk models.
Dynamically simulated tropical storms in a changing climate and their impact on the assessment of future climate risk
Professor Pier Luigi Vidale, Dr Kevin Hodges, Dr Jane Strachan and Matt Foote (Willis Re)
Detailed project description (PDF)
Extreme weather events, such as tropical cyclones, account for over 75% of insured losses due to natural catastrophes. Understanding how different modes of climate variability influence and interact with tropical cyclone activity holds huge potential for the insurance industry and the risk assessment of extreme events. By using high-resolution global climate model simulations, which are now able to credibly simulate tropical cyclones, we can investigate the impact of different modes of large-scale climate variability on tropical cyclone activity in terms of location, frequency and severity. Model simulation results will be used alongside high resolution observations and reanalysis. We are already working with the insurance industry to integrate climate model results into the industry risk assessment process, and this studentship will add invaluable research. This studentship has been proposed to be CASE supported by Willis Re, and will build on the already thriving relationship between Reading climate science and the insurance industry.
Effective atmospheric modelling for space geodesy
Professor Geoffrey Wadge (Project based in ESSC)
Space geodesy using radar interferometry (InSAR) has revealed a whole spectrum of deformation at the earth's surface. However, all but the largest signals are subject to phase delay noise due to the variable refractivity of the atmosphere. There is an increasing effort to mitigate the effects of radar wave delay on InSAR measurements of ground motion. This includes the use of time series and other statistical methods. Another approach has been pioneered at Reading - the use of forward atmospheric models of water vapour at high spatial resolution. Recent results show that this approach works well in modelling the non-turbulent component of the atmosphere, less well in capturing the dynamic, turbulent part. This studentship will address the comparative practical benefits of pursuing a forward atmospheric model to very high spatial resolution (~300 m) via a series of nested domains and to precise timing, versus coarser models and calibration with other data (e.g. GPS measurements of water vapour delay). The Met Office Unified Model (or WRF) will be used to drive the high-resolution models with ECMWF analysis results as the initial state. These models will be run for a variety of targets involving colleagues within the National Centre for Earth Observation, including the island of Montserrat. This NERC studentship will suit someone with a strong quantitative background in geophysics or meteorology. Close liaison with workers at the JCMM in Reading, NCEO Oxford and Glasgow, and the Montserrat Volcano Observatory will be required. Training in InSAR and/or mesoscale atmospheric modelling will be given as necessary.
Novel mixing schemes in ocean models
Dr Paul Williams and Professor Jonathan Gregory
Detailed project description (PDF)
Ocean eddies are swirling vortices that contain 99% of the ocean's kinetic energy. They play a crucial role in mixing temperature and salinity, and hence in controlling ocean dynamics and climate. However, the eddies are too small to be resolved by state-of-the-art computer models of the global ocean circulation. Traditionally, the mixing caused by the unresolved eddies is represented (or parameterized) as a diffusion process. Whilst this is a reasonable first approximation, there is new evidence that eddies may in fact behave non-diffusively or even anti-diffusively. This project will develop novel eddy mixing schemes, which add random (or stochastic) perturbations to the traditional diffusion representation. The project will implement and test the new schemes in ocean general circulation models, and will assess the impacts on ocean circulation and variability.
How do jet stream changes affect the propagation of Rossby waves?
Dr Tim Woollings
Detailed project description (PDF)
In the middle latitudes, low-frequency atmospheric variability mostly arises from two processes: shifts in the jet streams and large-scale Rossby waves. These processes lead to dramatic changes in the weather from week to week and also in the climate from one decade to the next. This project aims to investigate the link between these two processes by performing experiments with a simple climate model. Rossby waves consist of air masses hundreds of kilometres across moving northward and southward and they tend to become focused on the jet streams, which are themselves displaced north and south. The central question to be answered is how do changes in the jet streams affect the large-scale, low-frequency Rossby waves which propagate along them. Specific questions are: 1) How do shifts of the Atlantic jet stream affect the propagation of waves around the globe? 2) How do biases in climate models' representation of jet streams affect their ability to represent patterns of Rossby wave variability? 3) As the jet streams change under climate change how will patterns of Rossby wave variability be affected?