[Wrf-users] TKE and velocity perturbation output?

[Feng Liu]

Anders,
The option of km_opt is about calculation of turbulent diffusivity. If you want to have TKE in your output, you need to (1) use PBL schemes of TKE-related closure such as Mellor-Yamada-Janjic TKE scheme, MYNN 2.5/3rd  level  schemes; (2) to modify entries in IO column for TKE output in Registry file.  I hope that is helpful.
Feng

From: wrf-users-bounces at ucar.edu [mailto:wrf-users-bounces at ucar.edu] On Behalf Of Anders A Nottrott
Sent: Thursday, September 01, 2011 1:13 PM
To: wrf-users at ucar.edu
Subject: [Wrf-users] TKE and velocity perturbation output?

Hello All,

I am running some idealized LES cases for a convective ABL over a flat surface.  I was wondering if it is possible to get the resolved scale TKE as an output variable.  It seems to me that using km_opt=2 in the 'namelist' should give the resolved TKE as an output, but I do not find it in my netcdf output file.  I found the following in the ARW description document:
"Optionally, turbulent kinetic energy and any number of scalars such as water vapor mixing ratio, rain/snow mixing ratio, cloud water/ice mixing ratio, and chemical species and tracers."
Maybe this is only referring to the output obtained when using a PBL scheme?
Also is it possible to get information about the velocity perturbation as an output (e.g. u', v', w' or maybe the second moment)? I believe that the U, V, W output variables are the full velocities.  If I have to compute TKE and velocity fluctuation in post processing then I will have a lot of output data from the WRF run and post processing will be memory intensive.

Regards,

Anders Nottrott
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