Impact and feedbacks of turbulent mixing of heat around melting ice in Antarctic waters

Prof Andy Gooday, Alexander Brearley, Main Supervisor, British Antarctic Survey (BAS), https://www.bas.ac.uk/profile/jambre/; Hugh Venables, BAS, https://www.bas.ac.uk/profile/hjv/; Kate Hendry, BAS, https://www.bas.ac.uk/profile/kathen/; Mike Meredith, BAS, https://www.bas.ac.uk/profile/mmm/

Project Overview 

The project will analyze novel underwater glider, mooring and hydrographic data to understand ocean mixing in the West Antarctic and its impact on the melting of both sea ice and marine terminating glaciers. Links to global atmospheric datasets will also be made to elucidate the key controlling mechanisms.

Project Description 

The West Antarctic Peninsula (WAP) is a highly dynamic region that has undergone significant changes in atmospheric temperature, sea ice and glacial ice over the past 40 years. Much of this variability is driven by the ocean, where warm Circumpolar Deep Water intrudes onto the shelves and is modified by mixing before reaching glaciers and ice shelves at the coast. Quantifying the mechanisms behind these processes is key to understanding the heat budget of the WAP and its sensitivity to future atmospheric and ocean forcing. This project will seek to answer:

1.     What is the temporal variability in turbulent mixing and heat fluxes on the WAP?

2.     What are the key controls on this variability, including the role of winds, tides, sea ice and topography?

3.     How is this linked to broader scale atmospheric and ocean circulation, including the Southern Annular Mode/El Nino Southern Oscillation etc.?

To achieve these objectives, the student will analyze:

Novel ocean hydrographic glider data from Marguerite Bay, around the BAS base at Rothera, including temperature, salinity, microstructure and bio-optical 

  1. parameters;
  2. 21 years of bi-weekly temperature, salinity and pressure data from the Rothera time series;
  3. Four years of data from a mooring deployed at the mouth of Ryder Bay (close to Rothera), including temperature, salinity, finescale velocity, and turbulent dissipation rate from a structure function Acoustic Doppler Current Profiler (ADCP);
  4. How their local results scale up to the broader WAP by comparison with other in situ datasets and atmospheric reanalyses (e.g. ECMWF).

 

Location: 
British Antarctic Survey, Cambridge
Training: 

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 the British Antarctic Survey in Cambridge. Specific training will

include:

 

  1. The potential opportunity to participate in polar research cruises in the Southern Ocean/Antarctic, giving experience in the collection and processing of a variety of different physical oceanographic data. Note this is not required for successful completion of the PhD as the data are already collected.
  2. Training in the piloting of and processing of ocean glider data.
  3. Training in the processing and interpretation of microstructure data, and in time series analysis techniques.

 

Eligibility & Funding Details: 
Background Reading: 

Scott, Ryan M., Brearley, J. Alexander , Naveira Garabato, Alberto C., Venables, Hugh J., Meredith, Michael P.. (2021) Rates and mechanisms of turbulent mixing in a coastal embayment of the West Antarctic Peninsula. Journal of Geophysical Research: Oceans, 126. 26 pp. 10.1029/2020JC016861

Brearley, J. Alexander, Meredith, Michael P. , Naveira Garabato, Alberto C., Venables, Hugh J., Inall, Mark E.. (2017) Controls on turbulent mixing on the West Antarctic Peninsula shelf. Deep Sea Research II: Topical Studies in Oceanography, 139. 18-30. 10.1016/j.dsr2.2017.02.011

Venables, Hugh J., Meredith, Michael P., Brearley, J. Alexander . (2017) Modification of deep waters in Marguerite Bay, western Antarctic Peninsula, caused by topographic overflows. Deep Sea Research II: Topical Studies in Oceanography, 139. 9-17. 10.1016/j.dsr2.2016.09.005