A Comparison of HYCOM and MOM6 Vertical Coordinates
Alan
Wallcraft
Florida State University
Talk
HYCOM was the first widely used Arbitrary Lagrangian Eulerian (ALE) based ocean model and it demonstrated the viability of the ALE approach for the past 20 years. MOM6 is a similar model with updated numerics and coding style and a much larger developer base than HYCOM. ALE regridding is very flexible, but the primary approach of both models is to ""favor isopycnals"", with isopycnals effectively outcropping into fixed depth layers near the surface and at high latitudes.
HYCOM's pressure gradient is based on potential density with a thermobaricity correction and its vertical regridder, HYBGEN, is also based on potential density and on entrainment and detrainment to move layers to their target layer averages. MOM6 uses in-situ density, integrating the finite volume pressure gradient force using numerical quadrature, but its regridder, HYCOM1, is based on building a monotonic potential density profile and finding target interface densities on that profile.
We will compare and contrast the vertical coordinates of HYCOM and MOM6 in global and regional configurations.
HYCOM's pressure gradient is based on potential density with a thermobaricity correction and its vertical regridder, HYBGEN, is also based on potential density and on entrainment and detrainment to move layers to their target layer averages. MOM6 uses in-situ density, integrating the finite volume pressure gradient force using numerical quadrature, but its regridder, HYCOM1, is based on building a monotonic potential density profile and finding target interface densities on that profile.
We will compare and contrast the vertical coordinates of HYCOM and MOM6 in global and regional configurations.
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