WRF Model Family - atmos.uw.edu

Vertical Coordinates and Nesting Vertical Coordinate Systems Originally p and z: but they had a problemBC when the grid hit terrain!

Then eta, sigma p and sigma z, theta Increasingly use of hybrids e.g., sigmatheta Sigma

Sigma-Theta Hybrid and Eta Coordinates Ptop

Ptop =0 Pressure domain

=0 Sigma domain ground

ground =1 MSL

=1 Horizontal resolution of 12 km

12-km terrain Nesting Why Nesting?

Could run a model over the whole globe, but that would require large amounts of computational resource, particularly if done at high resolution. Alternative is to only use high resolution where you need itnesting is one approach.

In nesting, a small higher resolution domain is embedded with a larger, lower-resolution domain. Nesting

Can be one-way or two way. In the future, there will be adaptive nests that will put more resolution where it is needed. And instead of rectangular grids, other

shapes can be used.