Understanding changes in monsoon rainfall and circulation in CMIP6 projections, NERC GW4+ DTP, PhD in Mathematics studentship Ref: 3313

About the award


Lead Supervisor

Prof Mat Collins University of Exeter College of Engineering, Mathematics and Physical Sciences

Additional Supervisors

Dr Rob Chadwick (Met Office)

Dr Hugo Lambert University of Exeter College of Engineering, Mathematics and Physical Sciences

Dr Chris Taylor Centre for Ecology and Hydrology

Location: University of Exeter, Streatham Campus, Exeter EX4 4QJ

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP).  The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five Research Organisation partners:  British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology, the Natural History Museum and Plymouth Marine Laboratory.  The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme please see http://nercgw4plus.ac.uk/

For eligible successful applicants, the studentships comprises:

  • An index-linked stipend for 3.5 years (currently £14,777 p.a. for 2018/19);
  • Payment of university tuition fees;
  • A research budget of £11,000 for an international conference, lab, field and research expenses;
  • A training budget of £4,000 for specialist training courses and expenses.

Up to 30 fully-funded studentships will be available across the partnership.

Students from EU countries who do not meet the residency requirements may still be eligible for a fees-only award but no stipend.  Applicants who are classed as International for tuition fee purposes are not eligible for funding.

Project details

Future changes in tropical precipitation have the potential to produce some of the most severe impacts of climate change. This is particularly true in monsoon regions - over two billion people in Asia alone are dependent on monsoon rainfall. Unfortunately, current projections of regional precipitation changes in the tropics are very uncertain across models, inhibiting adaptation planning and providing major challenges for the detection and attribution of observed tropical precipitation trends.

Dynamical shifts in the location of convection have been identified as the primary driver of precipitation change in monsoon regions. However, different monsoons respond in diverse ways, with for example India generally projected to get wetter but the North American monsoon region getting drier. This suggests that the balance of processes driving rainfall change differs between the various monsoon regions. Furthermore, model biases in simulating present-day monsoons imply reduced confidence in projections.

Project Aims and Methods
In order to reduce uncertainty in projections, it is first necessary to improve our understanding of which processes are most important in each region and to quantify the role of model biases. This can lead to emergent constraints.

A new set of experiments (co-ordinated by co-supervisor Chadwick), designed to isolate the influence of different aspects of CO2 forcing on regional climate change, is included in the forthcoming set of CMIP6 (Coupled Model Intercomparison Project phase 6 experiments). These will show the balance between the effects of uniform SST warming, patterned SST warming, direct CO2 radiative absorption, the plant physiological response to CO2, and sea-ice changes, for each model and region. Changes in mean climate, seasonality, and daily-scale rainfall will all be examined. The main research questions are:
1) Which aspects of CO2 forcing are most important for driving precipitation and circulation changes in each monsoon region, both for the CMIP6 ensemble mean and inter-model uncertainty?
2) Once the dominant processes are understood, can present-day observations be used to provide emergent constraints on monsoon projections?
3) How do present-day SST biases affect CMIP6 projections of water cycle change in monsoon regions?
Usual GW4+ training plus master-level lecture courses on geophysical fluid dynamics, weather and climate, research methodology. Access to Met Office short courses on modelling, weather and climate.


Fig.1 Indian tea plantation


Fig.2 Mathematical decomposition of precipitation change

References / Background reading list

Brown, J.R., Moise, A.F., Colman, R. and Zhang, H. (2016). Will a warmer world mean a wetter or drier Australian monsoon? J. Climate, 29, 4577-4596

Chadwick, R., Boutle, I. and Martin, G. (2013). Spatial Patterns of Precipitation Change in CMIP5: Why the Rich Do Not Get Richer in the Tropics. J. Climate, 26(11): 3803-3822.
Chadwick, R., Douville, H. and Skinner, C. (2017). Timeslice experiments for understanding regional climate projections: applications to the tropical hydrological cycle and European winter circulation. Clim. Dyn., DOI:10.1007/s00382-016-3488-6

Collins M, Knutti R, Arblaster J, Dufresne JL, Fichefet T, Friedlingstein P, Gao X, Gutowski WJ, Johns T, Krinner G, Shongwe M, Tebaldi C, Weaver A, Wehner M (2013) Climate change 2013: the physical science basis. Contribution of working group 1 to the fifth assessment report of the Intergovernmental Panel on Climate Change. Cambridge Univ. Press, pp 1054–1099

Li, G., Xie, S.-P., He, C. and Chen, Z. (2017). Western Pacific emergent constraint lowers projected increase in Indian summer monsoon rainfall. Nat. Clim. Change, DOI:10.1038/NCLIMATE3387
Seager R, Naik N, Vecchi GA (2010) Thermodynamic and dynamic mechanisms for large-scale changes in the hydrological cycle in response to global warming. J Clim 23(17):4651–4668

Taylor, Christopher M.; Belusic, Danijel; Guichard, Francoise; Parker, Douglas J.; Vischel, Theo; Bock, Olivier; Harris, Phil P.; Janicot, Serge; Klein, Cornelia; Panthou, Geremy (2017) Frequency of extreme Sahelian storms tripled since 1982 in satellite observations. Nature, 544 (7651). 475-478. 10.1038/nature22069

Webb M, Andrews T, Bodas-Salcedo A, Bony S, Bretherton C, Chadwick R, Chepfer H, Douville H, Good P, Kay J, Klein S, Marchand R, Medeiros B, Siebesma A, Skinner C, Stevens B, Tselioudis G, Tsushima Y, Watanabe M (2016) The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6. Geosci Model Dev. doi:10.5194/gmd-2016-70

Entry requirements

Applicants should have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK.   Applicants with a Lower Second Class degree will be considered if they also have Master’s degree.  Applicants with a minimum of Upper Second Class degree and significant relevant non-academic experience are encouraged to apply.

Candidate requirements
Strong mathematics and/or physics background essential e.g. masters-level degree or 1st class BSc. Research project experience in climate desirable, but not essential.

All applicants would need to meet our English language requirements by the start of the  project http://www.exeter.ac.uk/postgraduate/apply/english/.

How to apply

In the application process you will be asked to upload several documents.  Please note our preferred format is PDF, each file named with your surname and the name of the document, eg. “Smith – CV.pdf”, “Smith – Cover Letter.pdf”, “Smith – Transcript.pdf”.

  • CV
  • Letter of application outlining your academic interests, prior research experience and reasons for wishing to undertake the project.
  • Transcript(s) giving full details of subjects studied and grades/marks obtained.  This should be an interim transcript if you are still studying.
  • If you are not a national of a majority English-speaking country you will need to submit evidence of your current proficiency in English.
  • Two References (applicants are recommended to have a third academic referee, if the two academic referees are within the same department/school).

Reference information
You will be asked to name two referees as part of the application process.  It is your responsibility to ensure that your two referees email their references to pgrenquiries@exeter.ac.uk, as we will not make requests for references directly; you must arrange for them to be submitted by 7 January 2019

References should be submitted to us directly in the form of a letter. Referees must email their references to us from their institutional email accounts. We cannot accept references from personal/private email accounts, unless it is a scanned document on institutional headed paper and signed by the referee.

All application documents must be submitted in English. Certified translated copies of academic qualifications must also be provided.

The closing date for applications is midnight on 7 January 2019.  Interviews will be held between 4 and 15 February 2019.

If you have any general enquiries about the application process please email pgrenquiries@exeter.ac.uk.  Project-specific queries should be directed to the supervisor Prof Mat Collins.

Data Sharing
During the application process, the University may need to make certain disclosures of your personal data to third parties to be able to administer your application, carry out interviews and select candidates.  These are not limited to, but may include disclosures to:

  • the selection panel and/or management board or equivalent of the relevant programme, which is likely to include staff from one or more other HEIs;
  • administrative staff at one or more other HEIs participating in the relevant programme.

Such disclosures will always be kept to the minimum amount of personal data required for the specific purpose. Your sensitive personal data (relating to disability and race/ethnicity) will not be disclosed without your explicit consent.


Application deadline:7th January 2019
Value:£14,777 per annum for 2018-19
Duration of award:per year
Contact: PGR Enquiries pgrenquiries@exeter.ac.uk