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Mozambique Channel Eddies in GCMs: A question of resolution and slippage

Quartly, G.D.; de Cuevas, B.A.; Coward, A.C.. 2013 Mozambique Channel Eddies in GCMs: A question of resolution and slippage. Ocean Modelling, 63. 56-67. 10.1016/j.ocemod.2012.12.011

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Abstract/Summary

Hydrographic observations in the 21st century have shown that the flow within the Mozambique Channel is best described by a series of large poleward-propagating anticyclonic eddies, rather than, as previously thought, a continuous intense western boundary current. The portrayal of this region in various runs of the NEMO 75-level model is found to vary between those two descriptions depending upon the resolution used and the implementation of the model's lateral boundary conditions. In a comparison of 1/4 ̊ resolution runs, the change of these conditions from free-slip to no-slip leads to the mean southward flow moving further offshore, with greater variability in the zonal and meridional velocities as the flow organises itself into eddies, and a reduction in total transport. If a realization of a model is unable to get these aspects of the physical flow correct, then this will significantly reduce its ability to show a realistic biological signal or long-term response to climate change. Further south, beyond Durban, the application of no-slip conditions similarly causes the mean Agulhas Current to lie further offshore, making it much more able to simulate Natal Pulses.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.ocemod.2012.12.011
Programmes: NOC Programmes
ISSN: 14635003
Additional Keywords: Indian Ocean: Mozambique Channel, NEMO, Spatial resolution, Boundary conditions, Stability, Natal Pulse (Current meandering)
Date made live: 07 Jan 2013 14:50 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/446712

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