[Wrf-users] Specifiying the geostrophic wind in idealized WRF-LES case

[Lin Mou]

Hi all,


I am trying to setup a case of neutral boundary layer driven by a desired geostrophic wind. When I check  the /test/em_les/Readme.les I find the following instruction:


"To simulate a CBL with a mean wind, change the initial wind profile in the input sounding. When pert_coriolis= true is set in the namelist, there is no need to include the geostrophic wind terms in the right-hand sides of the u and v equations for LESs with non-zero geostrophic wind."


I fail to understand why the geostrophic term is not needed to be added here. From my understanding (and trial) pert_coriolis= true just turned on the Coriolis effect in the simulation. But since the geostrophic forcing term should take the form of Du/Dt = f(v-v_g), Dv/Dt = f(u-u_g)  in the momentum equation, I don't quite understand why this case could simulate a non-zero geostrophic wind without adding any new term? What geostrophic wind speed did it specified here then?


Thank you very much for your help.


Regards,

Mou Lin

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