[Wrf-users] About the idealized large eddy simulation code

Li Xianxiang lixx at smart.mit.edu
Fri Jul 17 06:18:08 MDT 2009


I am considering to do some idealized simulation of PBL using WRF V3.1, 
so I read the initialization code of test/em_les case 
dyn_em/module_initialize_les.F and the paper Moeng et. al. (07) on MWR. 
However, some questions arise when I compare the paper and the code:

1. The paper mentioned 'the roughness length is 0.16 m' on pp 2298, but 
I can't find anywhere to specify the roughness length in the above code 
or namelist.input.

2. The default case in test/em_les seems to be the case F (free 
convection) in Moeng et.al. (07). But in the namelist.input, there is a 
tke_heat_flux=0.24 specified, and from module_initialize_les.F, the 
surface temperature was set to be 5 K warmer than the air temperature at 
the initial time. This means there are both heat flux and high surface 
temperature specified in this case. The README.les file in test/em_real 
directory doesn't mention this. So I am confused if this is an omission.

3. In the paper a new two part SGS model was implemented. I wonder if 
this version of SGS model has been implemented in WRF V3.1?

4. Why the specified tke_heat_flux is in the unit of W.m/s? What's the 
consideration for this? If we want to specify a heat flux of 300 W/m^2, 
we have to divide it by rho*C_p, which is inconvenient.

5. Is the tke_heat_flux the total flux or sensible heat flux?

Many thanks for your attention.

Xianxiang Li

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