PLEASE NOTE: Application deadline date 08 Jan 2024. Applications are no longer being accepted for this project
Project Overview
Antarctic Intermediate Water (AAIW) is a water mass with global distribution, storing carbon and heat away from the atmosphere. Yet, there is no consensus on how this water mass is renewed by surface processes and how it is influenced by, and feedbacks on, climate change. This project will investigate how AAIW is formed and how it is changing.
Project Description
The Antarctic Intermediate Water (AAIW) is formed in the Southern Ocean and ventilates the global ocean lower pycnocline, where it appears as a distinct salinity minimum. In the AAIW source region: (i) ocean warming has been registered for recent years (at least during the second half of 2010s compared with pre-2005 records), (ii) westerlies have been intensified, and (iii) sea ice extension has reduced in recent years. Therefore, AAIW is a sensitive water mass for climate changes and can propagate these changes into the ocean interior. Although AAIW is found globally, several lines of evidence suggest that air-sea fluxes drive the net formation of only a small volume of water in the AAIW density range, which opens the questions: How is the AAIW layer ventilated? Does AAIW contribute to the meridional overturning circulation at all? How do climate changes affect the properties and subduction of this water mass?
This project will use a vast range of observations, ocean modelling and reanalysis to investigate the following specific questions regarding the AAIW. (1) Is AAIW formed everywhere in the Southern Ocean, or it is formed in the Southeast Pacific and then advected toward other basins? (2) Is this formation driven by surface fluxes or internal mixing processes? How does mixing contribute to determining AAIW properties in different basins? (3) How do changes in the wind patterns and sea ice extension in the Southern Hemisphere affect or will affect the rates of ventilation of AAIW? Unravelling these new and fundamental information about the AAIW characteristics and formation is essential to better understand processes and impacts on the global ocean circulation and how the ocean takes up and retains heat and carbon.
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at Ocean and Earth Science. Specific training will include:
- Training in handling large oceanographic datasets (both in situ and modelling)
- Develop programming skills (Python, Matlab)
- Use of Lagrangian tracking tools (e.g. oceanparcels) applied to ocean model output
- Opportunity to present their work at international conferences.
- Possibility to attend fieldwork on a scientific cruise.
- Regular interaction with co-supervisors and possibility to spend weeks/months in the partner institutions.
- Attend relevant summer schools.
- Abernathey et al. (2016). Water-mass transformation by sea ice in the upper branch of the Southern Ocean overturning. Nature Geoscience, 9, doi: 10.1038/ngeo2749.
- Evans et al. (2018). The Cold Transit of Southern Ocean Upwelling. Geophysical Research Letters, 45, doi: 10.1029/2018GL079986.
- Portela et al. (2020). Interior Water-Mass Variability in the Southern Hemisphere Oceans during the Last Decade. Journal of Physical Oceanography, 50, doi: 10.1175/JPO-D-19-0128.s1.
