Supervisors:
Prof Alberto Naveira-Garabato, Dr. Matthew Palmer (NOC), Prof. Mark Inall (SAMS), Dr. Pierre Testor (LOCEAN, Paris)
Turbulence is, by its very nature, chaotic and sporadic. Understanding turbulence and turbulent mixing is however, critical to accurately predict ocean dynamics, mixed layer depth, biological productivity, air-sea gas transfer and the global carbon cycle. Recent developments (Palmer et al, 2015) have shown ocean gliders to be excellent platforms for measuring turbulence. These robots represent a real step change in ocean mixing measurements however, there remains the need to provide similar resolution measurements of the processes driving or controlling mixing. Newly equipped ocean gliders with integrated current velocimeters (ADCPs) offer the potential to measure ocean current velocities alongside density structure and turbulence at fine scales. This project will develop the analytical methods to measure current velocity and shear from ocean gliders at the appropriate length and time scales to capture the transition between laminar and turbulent ocean flows and close the local turbulent kinetic energy budget. The student will use this new capability to advance understanding of key ocean fluxes that are critical for understanding the Earth system, and so have the potential for high impact outputs.
Data for this project will come from combined deployments of the NOC and Royal Navy fleets of autonomous ocean gliders. The student will firstly develop the techniques required to process glider-mounted ADCP data to produce accurate measurements of current velocity and vertical shear. These techniques will then be used to process and analyse coincident density, velocity and turbulence data within a variety of forcing scenarios to build an improved picture of how turbulence develops in our oceans and the consequences of this mixing to address the primary objective of this project; to improve capability in predicting ocean turbulence and mixing in stratified and near-surface regions.
This PhD will produce a unique dataset, offering laboratory-scale resolution of fine and micro-scale ocean processes that will be used to develop new insight into the mechanistic control of turbulent mixing. As such, these data will be of the highest value for validation of ocean and Earth system modelling studies and will feed directly into ongoing research being undertaken by the supervisors that aims to improve parameterisation of turbulent processes in the ocean.
The NEXUSS CDT provides state-of-the-art, highly experiential training in the application and development of cutting-edge Smart and Autonomous Observing Systems for the environmental sciences, alongside comprehensive personal and professional development. There will be extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial / government / policy partners. The student will be registered at the University of Southampton and hosted at the National Oceanography Centre in Liverpool.
Specific training will include:
Background Reading:
Palmer, Inall et al (2015) Turbulence and Mixing by Internal Waves In The Celtic Sea Determined From Ocean Glider Microstructure Measurements. J. Marine Systems
Palmer, Inall et al (2013), Variable Behavior In Pycnocline Mixing Over Shelf Seas. GRL, 40
Houpert L., P. Testor et al (2014) Seasonal cycle of the Mixed Layer, the Seasonal Thermocline and the Upper-Ocean Heat Storage Rate in the Mediterranean Sea derived from observations, Progress in Oceanography
To apply for this project, use the: apply for a NEXUSS CDT studentship