Evaluating two numerical advection schemes in HYCOM for eddy-resolvingmodelling of the Agulhas Current

[摘要] A 4th order advection scheme is applied in a nested eddy-resolving HybridCoordinate Ocean Model (HYCOM) of the greater Agulhas Current system for thepurpose of testing advanced numerics as a means for improving the modelsimulation for eventual operational implementation. Model validationtechniques comparing sea surface height variations, sea level skewness andvariogram analyses to satellite altimetry measurements quantify thatgenerally the 4th order advection scheme improves the realism of the modelsimulation. The most striking improvement over the standard 2nd ordermomentum advection scheme, is that the southern Agulhas Current is simulatedas a well-defined meandering current, rather than a train of successiveeddies. A better vertical structure and stronger poleward transports in theAgulhas Current core contribute toward a better southwestward penetration ofthe current, and its temperature field, implying a stronger Indo-Atlanticinter-ocean exchange. It is found that the transport, and hence thisexchange, is sensitive to the occurrences of mesoscale features originatingupstream in the Mozambique Channel and southern East Madagascar Current, andthat the improved HYCOM simulation is well suited for further studies ofthese inter-actions.

[学科分类] 海洋学与技术