UW-NMS Model Lower Boundary Conditions

TERRAIN (Step Topography Condition)

• Grid box blocked out when topography exceeds midpoint.
• Velocity and velocity tendency defined on edge of blocked out grid box is zero.
• All vorticity on an interface of terrain box set to Earth's value.
• Fluxes defined on edge of blocked out grid box are zero. This includes intermediate fluxes such as within filtering scheme.
• High order differencing schemes reduced in order as terrain box is approached from above or laterally.
• Kinetic energy is zero within blocked out box.

SURFACE FLUXES

• N-level soil model (Usually use 5 levels). Snow accomadated as a special soil type.
• Externally specified sea surface temperature
• Louis(1979) surface layer modified to include micro layer
• Surface layer fluxes enter model through lower boundary condition on vertical turbulent mixing