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  Novel current meters on ocean gliders: using electromagnetic induction to measure flow and subsurface glider motion (HALLUENV18NEX)


   School of Environmental Sciences

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  Dr Robert Hall, Dr Bastien Queste, Dr Eleanor Frajka-Williams, Dr Rolf Lueck  No more applications being accepted  Competition Funded PhD Project (European/UK Students Only)

About the Project

Ocean gliders are an essential component of coastal and deep sea oceanographic experiments. These autonomous vehicles ‘fly’ between the surface and seabed in a sawtooth pattern by changing their density relative to the surrounding water. GPS is used to determine their location and average horizontal velocity, but GPS can only operate at the surface. This uncertainty in subsurface motion is problematic for navigation and for calculating key oceanographic variables such as salinity, current velocity, turbulent mixing.

The glider can be equipped with a traditional heavy and power-hungry current meter to measure its speed – a new type of current meter has recently been developed that is small, light and power-efficient, working on the principles of electromagnetic (EM) induction. This PhD project will investigate the capabilities of EM current meters on gliders and improve measurements turbulent kinetic energy (TKE) dissipation rate from glider-collected shear microstructure data.

The student will use an EM current meter integrated with the microstructure sensor system of a Kongsberg Seaglider. The current meter will be aligned so that it measures the axial speed of the glider through the water. Accurate axial speeds are required to convert glider timeseries data into a spatial field and to process shear microstructure data. Although axial speed can be estimated using hydrodynamic models, at present these models cannot be ground truthed.Specific objectives for this PhD project are:

1) Test a Seaglider with EM current meter in a recirculating flume and compare measured speeds to acoustic Doppler velocimeter derived free flow velocities.
2) Process and quality-control EM current meter data from microstructure Seaglider trials and science missions.
3) Direct measurements of axial speed will be used to:
a. Calculate TKE dissipation rate from shear microstructure without resorting to estimates from the Seaglider flight model.
b. Constrain the flight model to improve the quality of the salinity data and dive-average current velocities.

Requirements:
Engineering, Geophysics, Mathematics, Oceanography or Marine Science, or Physics.

Training:
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 East Anglia (UEA), with periods of training at the University of Southampton. The student will join the UEA Glider Science Group (www.ueaglider.uea.ac.uk). Specific training will include:
• Autonomous ocean glider data processing, quality control, and analysis techniques
• Microstructure data processing and analysis techniques
• Ocean glider operations, including preparation, deployment, and piloting
• Participation in oceanographic research cruises
• Numerical modelling of dynamic ocean processes
• Presentation of research at international conferences and workshops

Secondary supervisors: Dr Bastien Queste (UEA, Environmental Sciences), Dr Eleanor Frajka-Williams (University of Southampton, Ocean and Earth Science), Dr Rolf Lueck (Rockland Scientific and University of Victoria, Canada).

For further information, please visit www.enveast.ac.uk/nexuss

For more information on the supervisor for this project, please go here: https://www.uea.ac.uk/environmental-sciences/people/profile/robert-hall
Type of programme: PhD
Start date of project: October 2018
Mode of study: Full time or part time
Length of studentship: 3 years, 8 months.

Acceptable first degree: A numerate discipline, e.g. Engineering, Geophysics, Mathematics, Oceanography or Marine Science, or Physics.

Minimum entry requirement: 2:1 or equivalent.


Funding Notes

Successful candidates who meet RCUK’s eligibility criteria will be awarded a NERC/EPSRC studentship - in 2017/18, the stipend is £14,553. In most cases, UK and EU nationals who have been resident in the UK for 3 years are eligible for a stipend. For non-UK EU-resident applicants NERC funding can be used to cover fees, RTSG and training costs, but not any part of the stipend. Individual institutes may, however, elect to provide a stipend from their own resources.

References

(i) Fer, I., A. K. Peterson, and J. E. Ullgren, 2014: Microstructure measurements from an underwater glider in the turbulent Faroe Bank Channel overflow. Journal of Atmospheric and Oceanic Technology, 31, 1128–1150, doi:10.1175/JTECH–D–13–00221.1.
(ii) Palmer, M. R., G. R Stephenson, M. E. Inall, C. Balfour, A. Dusterhus, and J. A. M. Green, 2015: Turbulence and mixing by internal waves in the Celtic Sea determined from ocean glider microstructure measurements, Journal of Marine Systems, 144, 57-69, doi:10.1016/j.jmarsys.2014.11.005.

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