The summer extent of Arctic sea ice has experienced a significant decrease during the last several decades. This reduction is driven by a combination of mechanical and thermal processes in the atmosphere, ocean and sea ice itself. Mechanical sea ice floe breakup is caused by (i) the large-scale deformation pattern in the ice cover (e.g. shear), (ii) the random jostling motion of the floes, caused by turbulent and local variations in wind and/or ocean stresses, and, (iii) especially near the ice edge, over the so-called ‘marginal ice zone’ (MIZ), by incoming ocean waves and tidal motions. As floes break up, the total perimeter (edge length) of a given area of sea ice increases, leading to more rapid lateral melting. The reduction in floe size weakens the resistance of the ice cover to the incoming wave field, thus promoting further jostling motion between the floes, and further lateral melting.
Turbulent ocean mixing depends both on surface forcing and the type and extent of sea ice cover. Pack ice suppresses waves, significantly reducing wave-induced mixing of the upper ocean. In the present-day Arctic, however, the reduced summer sea ice cover is expected to lead to increased height of swell waves and swell interaction with ice keels may increase mixing. This increased turbulent mixing will further promote sea ice disintegration by making more oceanic heat available for sea ice melt, increasing the area of highly fragmented sea ice in the MIZ and introducing a positive feedback in the retreat of summer sea ice. In most Ocean General Circulation Models (OGCMs) wave mixing is neglected in the presence of sea ice and the effect of wave-induced mixing in the MIZ is ignored. This introduces a substantial error in both operational forecasts and climate simulations.
The FP7 project Ships and Waves Reaching Polar Regions (SWARP) will develop techniques for forecasting sea ice and waves in the Arctic MIZ. Waves in ice are major hazards for vessels and industrial activities in the polar seas and their impact will increase as marine industries expand in the high latitudes. Despite the many measurements of waves and ocean mixing in sea ice areas being taken during ice camps, presently there is no real-time wave information or forecasts in sea ice covered areas or real-time information on their effects on sea ice and the ocean. The SWARP project will help to fill this gap by developing and implementing sea-ice/ocean models that enable simulation of the pack ice zone and the MIZs.
The student will interact with project partners and scientists from the National Oceanography Centre (NOC), University of Reading and University of Southampton. Expertise/advice in waves in the ice-covered areas will be provided by SWARP project participants Prof Vernon Squire (University of Otago, NZ), Dr Tim Williams (Nansen Environmental and Remote Sensing Center, NERSC, Norway) and Dr Fabrice Ardhuin (Institut français pour la recherche sur la mer , IFREMER, France), one of the main developers of the WaveWatch III model and from NOC in-house expertise in running the WaveWatch III model. The student will also benefit from scientific communications within the NEMO System and NEMO Wave Group (http://www.nemo-ocean.eu/).
NOC-Southampton is the UK’s largest oceanographic centre and one of the world leading oceanographic institutions. The University of Reading is a world-leading centre in atmospheric modelling. The successful candidate will benefit from the research environment and mentoring at both universities which offer various courses at the Masters and PhD levels, including atmosphere dynamics, meteorology, sea ice physics, climate modelling, programming, etc. The student will gain training in geophysical fluid mechanics, ocean model parameterisation and assessment and in the running of climate model experiments. He/she will receive training in using coding languages such as Matlab, Python and Fortran, in working in Unix/Linux environment and using netcdf libraries where appropriate. The training programme will be individually tailored to the student’s needs.
This project has FP7 support funding via the project ‘Ships and Waves Reaching Polar Regions’ (SWARP). The studentship fees will be covered by the University of Southampton (SOES) at UK/EU home rates only. Non-EU students are required to match the difference between the UK home and overseas rates for the studentship fees.
The successful candidate will have a degree, 2.(i) at least, in physics, applied mathematics, engineering, or a similar numerate discipline. He/she will demonstrate an aptitude for learning new skills and for using physical principles to solve applied problems. No prior oceanographic knowledge is required. The main approach in the PhD project will be numerical modeling and experience in programming in high-level languages, such as Fortran or C is welcomed, although not essential.