2004 LOM Workshop

Tuesday 9:00 - 9:20 a.m.

Alternative numerical scheme for the primitive equations in HYCOM

Mats Bentsen
Nansen Environmental and Remote Sensing Center
mats.bentsen@nersc.no

ABSTRACT

---

A numerical scheme for the inviscid, unforced primitive equations for an ocean model with isopycnic layers, will be presented. The proposed scheme uses a two-level time-stepping scheme based on a total variation diminishing second order Runge-Kutta method with modifications to the treatment of the Coriolis and Montgomery potential gradient terms for stability reasons and, in addition, a more accurate representation of the geostrophic balance. The scheme used for the transport terms in the layer equations, is based on a weighted essentially non-oscillatory scheme. A two-dimensional barotropic equation system is integrated with a time step dictated by the speed of the fast external gravity waves. These fast motions are filtered out of the layer equations which then may be integrated with a time step sufficient to resolve the much slower three-dimensional internal motions. The implementation of this split time stepping method is shown to be stable for a linearized and simplified system. Results from simulations of an idealized frontogenesis experiment and a simple wind-driven basin-scale configuration will be shown.

---

LOM Users' Workshop, February 9-11, 2004