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em_les: how can we set the environmental wind?

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The description of em_les is the:

"This test case produces a large-eddy simulation (LES) of a free convective boundary layer (CBL). The environmental wind (or the initial wind profile) is set to zero in this default case.The turbulence of the free CBL is driven/maintained by the surfaceheat flux, which is specified in the namelist as tke_heat_flux=0.24(in MKS units)"

Can we set the tke_heat_flux=0, and let the flow to be driven by the environmental wind that always exist (instead of the initial wind profile)?

The ideal LES case is designed for free convective PBL, which is driven by the surface heating specified in namelist.
You can set tke_heat_flux = 0, and manage to maintain a constant wind field. In this case I suppose that the large eddy would be forced by surface stress. However, I am concerned that the environmental wind field will impose influences along the boundary, and such influences will propagate into the interior of the model domain, eventually affect the LES simulation.