Dr A Marzocchi, Prof A Naveira-Garabato, Dr G Nurser, Dr Andrew Meijers
No more applications being accepted
Competition Funded PhD Project (Students Worldwide)
About the Project
Project Rationale
The ocean is the largest carbon reservoir in the Earth system and it stores over 90% of the excess heat produced by anthropogenic activities. The rate at which both heat and carbon are absorbed by the ocean varies strongly, both in space and time, and the Southern Ocean is a key region for the uptake of both. However, we have limited skills in predicting how this will change in the future. Ice-ocean-atmosphere interactions are key in determining the rates of carbon and heat uptake by the ocean. Antarctic sea-ice formation/export and circumpolar westerly winds are the dominant surface forcings in the Southern Ocean, driving the upwelling and ventilation of the dense waters that fill most of the ocean interior and the formation of Antarctic Bottom Water, a key component of the global abyssal circulation. Polynyas – seasonal openings in the sea ice – are the other main contributors to the formation of deep and dense shelf waters around the Antarctic margins. However, Southern Ocean dynamics and circulation are poorly simulated in coupled climate models [1]. Even state-of-the-art simulations fail to represent ice-ocean-atmosphere interactions and biogeochemical processes adequately, and observations in these regions are scarce. This project will assess key Southern Ocean processes in a range of numerical models and evaluate these against available satellite and oceanographic measurements.
Methodology
Firstly, state-of-the-art simulations from the 6th Coupled Model Intercomparison Project (CMIP6) will be analysed to assess their performance in the Southern Ocean and their representation of key processes associated with deep water formation and circulation, such as winds and sea-ice dynamics. A number of metrics and statistical tools will be used, taking advantage of cloud-based computing capabilities [2]. Model output will be evaluated against the observational record and compared to a high-resolution model of the Southern Ocean.
Secondly, satellite along-track altimetry data in Antarctic sea-ice leads will be used to analyse the ocean’s response (sea level) inside polynyas.
The CMIP6 archive of simulations has recently become available and will contribute to the 6th assessment report of the Intergovernmental Panel for Climate Change (IPCC). In addition, the sea-ice satellites from the European and American space agencies have been aligned for the first time in 2020, which will provide unprecedented double measurements of sea-ice thickness and increase the accuracy of our estimates. These recent advances make such analysis especially timely. Finally, these combined results will be used to determine the effect of sea ice on ocean circulation and heat/carbon uptake, to improve our understanding of present and past trends and how these may vary in the future.
Training
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multidisciplinary 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 National Oceanography Centre and/or British Antarctic Survey.
Numerical modelling and ‘big-data’ analysis are among the most in-demand skills within international environmental research; this PhD will enable the student to develop proficiency in these techniques.
Specific training will include:
– Analysis of ‘big-data’ archives from state-of-the-art climate models and observations.
– Development/application of cloud-based computing capabilities and of statistical methods and machine learning techniques, with a focus on programming (e.g. Python)
– University of Southampton courses (e.g. Large-scale Ocean Processes, Computational Data Analysis, Climate Dynamics, Biogeochemical Cycles, Global Ocean Carbon Cycle)
– Opportunities to attend national and international conferences, workshops and summer schools (e.g. in collaboration with the UK Met Office)
– Opportunities to participate in Antarctic research cruises.
References
[1] Heuzé, C., et al. “Southern Ocean bottom water characteristics in CMIP5 models”. Geophysical Research Letters 40.7 (2013): 1409-1414. [2] Pangeo: A community platform for Big Data geoscience https://pangeo.io/