questions about Cumulus scheme

Topics related to current and future physics in the WRF as well as any problems you may have.

questions about Cumulus scheme

Postby wenwen » Sun Mar 12, 2017 4:40 am

I have some questions about wrf,as shown below:
① Why for dx≤3 km: probably do not need Cumulus scheme? Is there no convection in atmosphere?
② How do I get the tendency of the mixing ratios of ice due to the microphysics schemes?

Your help is greatly appreciated.


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Re: questions about Cumulus scheme

Postby twis91 » Fri Jul 14, 2017 7:53 pm


1) This is stuff related to parameterizations.
- Most of the Cumulus parameterization schemes (e.g. Arakawa-Schubert, 1974 or Tiedtke, 1989) assume that the convective cells are subgrid phenomena. If you imagine a usual thunderstorm it might be clear that it is often smaller than e.g. 10km x 10km grid size. At a certain point (you can discuss), the thunderstorms are kind of "resolved" by the grid and the parameterization does not work any more.
- Furthermore, at a certain resolution, the "individual clouds" are resolved or parameterized sucessfully by microphysics which replaces in that case the Cumulus parameterization (keyword: cloud resolving models).

2) You can add a new state variable to the Registry, if not existing and pass it through the modules. But I bet it should be there somewhere in the Registry.

Kind regards!
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