A non-hydrostatic numerical weather prediction model has been employed to simulate
idealised katabatic flows over a moderate slope and adjoining ice shelf. To be specific, the
topography of Coats Land and the adjoining Brunt Ice Shelf, Antarctica, have been used,
although this is typical of much of the Antarctic coastline. The RAMS (Regional
Atmospheric Modeling System) Version 4.3 has been adapted for simulations over
compacted snow, most notably through changes to the multi-layer soil model. The
simulations are initialised using clear-sky climatological conditions and at rest. A shallow
katabatic flow develops into a quasi steady-state after about 12 hours of simulation time. The
peak downslope winds are ~7 m s-1 at 30 m above the surface near the steepest part of the
slope. The flow depth ranges from 50 to 100 m down the slope. Over the ice shelf, the
katabatic flow peters out, while a pool of cold air develops, primarily through sensible heat
loss into the surface and partially balancing the net radiative heat loss to space. Near-surface
and sounding data from the model simulations compare well with archetypal and typical
katabatic flow observations; especially after some tuning of the model's turbulence
parameterisation. 
     An analysis of the downslope flow dynamics shows the buoyancy force is generally
balanced by the inertial force; except towards the foot of the slope, where the buoyancy force
is balanced by up-slope thermal wind forces due to the pool of cold air over the ice shelf.
Over time, the cooling of the ice shelf boundary layer leads to an apparent retreat of the
katabatic flow from the ice shelf and some way up the slope. The analysis explains the
observed surface climatology of Coats Land, where the persistent katabatic winds rarely reach
the Brunt Ice Shelf. The simulated katabatic flow moves from shooting to tranquil towards
the slope foot. This transition acts to trigger a train of internal gravity waves which propagate
energy upwards away from the katabatic flow jump. Previous studies have also found
shooting to tranquil katabatic flow transitions, so to generalise these findings would suggest
that internal gravity wave generation is ubiquitous around much of coastal Antarctica and
Greenland.