NCAR Summer School, 13 August 2008
Regional Climate Models
Some examples of parameterization
¥Turbulence:
¥If the low layers are warmer than the upper layers, thermal turbulence will occur (warm air rises through cold air).  Turbulent mixing acts on scales of millimeters to a few hundred meters.
¥Parameterization: Gradually mix the layers if temperature decreases strongly with height between layers.
¥Deep convection (thunderstorms):
¥Thunderstorms develop when the atmosphere is warm and moist near the surface and cool aloft, and if condensation occurs.  Motions are on scales of tens of meters to a few km.
¥Parameterization:  Vertically rearrange heat and moisture if the lower levels are sufficiently warm and moist and grid scale motion is upward (promotes condensation). Deposit leftover moisture as rain.