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C411: Multi-scale Dynamics in the Southern Ocean (Lead Supervisor: John Taylor, DAMTP)

Supervisor: John Taylor (DAMTP)  

Importance of the area of research:

Ocean currents in the Southern Ocean play a major role in the Earth's climate system. The Southern Ocean exhibits a kaleidoscope of swirling turbulent eddies on a wide range of scales. The largest of these eddies (termed `mesoscale' and roughly 20-100 km in diameter) play a major role in transporting heat toward Antarctica and their dynamics is strongly constrained by the Earth's rotation. Mesoscale eddies are surrounded by a rich collection of smaller features (sub-mesoscales) with scales between 100m and 10km, including eddies, fronts, and filaments which spin off of the larger eddies and currents. Sub-mesoscales are known to generate strong vertical motion and subduct surface water into the ocean interior. Sub-mesoscales are too small to be resolved in climate models, making it highly important to understand their dynamics and their interactions with larger scale motion. At the same time, little is known about how mesoscale and sub-mesoscale eddies interact, particularly in the poorly sampled Southern Ocean.

Project summary:

The objective of this project is to develop a rigorous mathematical description of the multi-scale interactions between mesoscale eddies and sub-mesoscales in the Southern Ocean. Several newly available datasets including a recent observational cruise and an accompanying ultra high resolution ocean model simulation put this challenging task within reach. Achieving the objective will require a creative blend of physical reasoning, mathematics, and numerical computations.  Once developed, the multi-scale model will be used to improve the representation of mesoscale and sub-mesoscale dynamics in large scale ocean and climate models.

What the student will do:

The student will begin by analyzing existing datasets including newly available observations and numerical simulations. A local scale-dependent filtering technique will be used to distinguish between the wide range of scales involved in the dynamics. Particular focus will be paid to quantifying the energy transfer between the various scales. Based on this analysis, a multi-scale mathematical model will be developed to describe these interactions as a function of regional ocean conditions. Idealized numerical experiments will be conducted in order to test and refine the mathematical model. The results will then be communicated to ocean modelers with the aim to improve the state of the art ocean and climate models.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Bachman, S. D., Taylor, J. R., Adams, K. A., & Hosegood, P. J. (2017). Mesoscale and Submesoscale Effects on Mixed Layer Depth in the Southern Ocean. Journal of Physical Oceanography, 47(9), 2173-2188.

Adams, K. A., Hosegood, P., Taylor, J. R., Sallée, J. B., Bachman, S., Torres, R., & Stamper, M. (2017). Frontal circulation and submesoscale variability during the formation of a Southern Ocean mesoscale eddy. Journal of Physical Oceanography, 47(7), 1737-1753.

McWilliams, J. C. (2016). Submesoscale currents in the ocean. In Proc. R. Soc. A (Vol. 472, No. 2189, p. 20160117). The Royal Society.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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