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Cambridge NERC Doctoral Landscape Awards (Training Partnerships)

Graduate Research Opportunities
 

Lead supervisor: Ali Mashayek, Earth Sciences

Co-supervisor: Colm Caulfield, DAMTP

Brief summary: 
This project studies the change in global patterns of small-scale ocean turbulence due to climate change and the feedback of such change onto the climate system.
Importance of the area of research concerned: 
Small-scale ocean turbulence induced by waves, eddies, and currents exists throughout ocean depths and plays an important role in the climate system through I) driving the deep ocean circulation by resurfacing of dense waters that form and sink in polar regions, II) the exchange of heat and carbon between the ocean and atmosphere, and III) redistribution of such tracers (among others, such as nutrients, pollutants, etc) globally and vertically into the depth where anthropogenic heat and carbon can be sequestered. Such turbulence is yet to be fully understood. To make matters worse, it is changing through the climate system and the changes feedback onto the climate system. Thus, there is urgency in identifying and quantifying the global changes to ocean turbulence patterns. Such changes are amplified in polar regions where ice melt, and temperature changes due to climate change have rapidly modified seawater density and surface winds over the past decades. The impacts of polar changes rapidly propagate through the globe, changing turbulence almost everywhere.
Project summary : 
This project is focused on identifying the change in the nature of turbulence on a global scale due to climate change. The project will employ outputs from ocean state estimates (https://ecco-group.org/) which assimilate the broadest possible set of in situ observations (e.g. ship-based, Argo floats, etc.) and remote sensing (e.g. satellite altimetry, sea surface temperature observations, etc) to produce a solution of ocean dynamics on a global scale over the past few decades. This project will use such estimates to relate the bulk properties (such as local velocity and density gradients) to turbulence estimates. Once achieved, the change in turbulence over the past decades due to climate variability will be studied. The project concerns how the change to turbulence I) changes the atmosphere-ocean exchange of anthropogenic heat and carbon and II) modifies the ocean circulation.
What will the student do?: 
The student will: - Learn about the sources of ocean turbulence - Learn how turbulence contributes to large-scale circulation and tracer budgets - Categorize the types of small-scale turbulence in the ocean by using a combination of fine-resolution ECCO products and direct observations of turbulence - Extend such categorization to coarser-resolution ECCO product which provides a few decades of climate evolution - Identify the global patterns of change in small-scale turbulence over the past few decades - Link the discovered changes to the uptake of anthropogenic heat and carbon - Link the discovered changes to changes in the ocean circulation
References - references should provide further reading about the project: 
Shi, H., Jin, F.F., Wills, R.C., Jacox, M.G., Amaya, D.J., Black, B.A., Rykaczewski, R.R., Bograd, S.J., GarcĂ­a-Reyes, M. and Sydeman, W.J., 2022, Science Advances, 8(18), https://doi.org/10.1126/sciadv.abm3468 (Look for "vertical mixing", "ocean mixing" as keywords)
Melet, A.V., Hallberg, R. and Marshall, D.P., 2022, In Ocean mixing (pp. 5-34). Elsevier, https://doi.org/10.1016/B978-0-12-821512-8.00009-8
Powell, D., 2016. Role of chaos in deep ocean turned upside down. , https://doi.org/10.1038/nature.2016.19455
Applying
You can find out about applying for this project on the Department of Earth Sciences page.