About the project
While palaeoclimate records suggest that Mediterranean Overflow Water (MOW) dramatically impacted the Atlantic Meridional Overturning (AMOC) circulation, its role in the modern ocean remains uncertain. In situ observations and numerical models will be used to explore impacts on the AMOC of recent and future changes in MOW properties and circulation.
In today’s ocean, the high salinity of the subpolar North Atlantic enables dense water formation by winter cooling, which feeds the Atlantic Overturning circulation (AMOC). Mediterranean Overflow Water (MOW) supplies salt to the North Atlantic, influencing the basin’s salinity budget and the AMOC.
Indeed, palaeoceanographic records and models show that changes in MOW can lead to changes in the AMOC, including a freshening-driven shutdown and dramatic climate change. As a result of anthropogenic climate change, the Mediterranean Sea is warming and becoming saltier at a much higher rate than the global ocean. The impact of such changes on the properties and fate of MOW and the future of the AMOC are unknown, but we hypothesise that MOW salinity increase could make AMOC resilient to freshening at subpolar latitudes.
In this project, you will test these ideas using novel observations and modelling datasets. Specifically, you will:
- use data from autonomous Argo floats to characterise variability in the properties and distribution of MOW within the North Atlantic over the past 25 years
- quantify the contribution of MOW mixing to the water mass transformations driving the AMOC
- using a suite of numerical models, you will investigate how MOW properties and pathways will change in the coming century, and the impacts for the AMOC
You will also be supervised by organisations other than the University of Southampton, including Prof Simon Josey from National Oceanography Centre.
Potential supervisors
Lead supervisor
Dr Bieito Fernandez Castro
Lecturer in Physical Oceanography
Research interests
- Turbulent mixing
- Ocean dynamics and circulation
- Ocean biogeochemical (carbon) cycles
Supervisors
Dr Nikolaos Skliris
Lecturer B
Research interests
- Water cycle change inferred from ocean salinity
- Mediterranean Sea climate variability & change (Overturning Circulation, Sea Level, Water Cycle, …)
- Impacts of ocean physics on marine ecosystemsÂ
Dr Alessandro Silvano
NERC Independent Research Fellow
Entry requirements
You must have a UK 2:1 honours degree or higher in a relevant subject.
You can also have its international equivalent.
International applications
If English is not your first language, you will need an International English Language Testing System (IELTS) overall score of 6.5, with a minimum of 6.0 in all components.
Visit our English language proficiency pages to find out about other qualifications we accept.
Fees and funding
This project is eligible for full funding. Learn more about the funding scheme here.
How to apply
You need to:
- choose programme type (Research), 2025/26, Faculty of Environmental and Life Sciences
- choose PhD in IGNITE (full time)
- add your supervisor in section 2
Applications should include:
- a personal statement
- your CV (resumé)
- 2 academic references
- degree transcripts to date
It is essential for overseas applicants to make contact with the lead supervisor prior to applying.
Contact us
Faculty of Environmental and Life Sciences
If you have a general question, email our doctoral college: fels-pgr-apply@soton.ac.uk.
Project leader
For an initial conversation, please email Bieito Fernández Castro b.fernandez-castro@soton.ac.uk.
