HPCx homepage
Services User support Projects Research About us Sitemap Search  
             
               
home > highlights > env1
spacer
hr
spacer

A study of Agulhas rings in a high-resolution ocean model

spacer

Vortex shedding has an important role in the global thermohaline circulation. The Agulhas Current is the strongest western boundary current of the southern hemisphere. Agulhas vortex rings move into the South Atlantic Ocean in a north-westerly direction. Present estimates are that roughly six Agulhas rings are being formed each year. These rings form an important link between the subtropical gyres of the South Atlantic Ocean and the Indian Ocean. This link is also thought to play an important role in the upper branch of the global thermohaline circulation.

These rings can be followed with satellite measurements of sea surface height, but complimentary research using realistic ocean models is essential to improve our understanding of the regional processes and hence of any possible changes in a warming environment.

 

 

The UK's global ocean model (OCCAM) is being run at an eddy-resolving resolution of 1/12 degree. This figure shows the sea surface height at the beginning of the year that has been used for the analysis. The Agulhas Current is centered at 24oE. The heavy dashed lines indicate the regions within the three Agulhas rings where Lagrangian particles have been seeded. The path of the three rings has also been indicated. The youngest (and largest) Agulhas ring is two weeks old. The ring in the middle was shed in mid-November, at the end of spring. The oldest ring was formed in midwinter of the first year.

 

The model integrations are carried out as part of Southampton Oceanography Centre's core strategic research program, which is supported by the Natural Environment Research Council (NERC). This work is just one example of the environmental research carried out using the NERC share of HPCx. Realistic simulations of our natural environment will continue to require resources capable of integrating complex numerical models and analysing the large volumes of data generated by such models. The level of realism that can now be achieved is providing an invaluable complement to observational programmes.

Impact of cooling on the water mass exchange of Agulhas rings
in a high resolution ocean model,
J Donners, S S Drijfhout and A C Coward,
Geophys Res Lett., (2004), 31, L16312

spacer
hr
spacer
http://www.hpcx.ac.uk/highlights/env1.html contact email - www@hpcx.ac.uk © UoE HPCX Ltd