What is the default lower boundary condition is for WRF?

Topics related to the dynamics/numerics of the WRF model
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badtanjil
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Joined: Fri Jan 31, 2020 11:06 pm

What is the default lower boundary condition is for WRF?

Post by badtanjil » Fri Sep 04, 2020 1:44 am

We are running a simple vortex case for hurricane with no surface layer and with constant viscosity on horizontal and vertical direction. We are giving periodic boundary conditions on X and Y direction on namelist.input file. There does not appear to be an option to set lower boundary conditions in the namelist file and we are getting output that indicates an inviscid wall boundary condition is enabled. We want to know where in the code the lower boundary condition is set and what variables (u,v,w, theta) are set to inviscid.

kwerner
Posts: 2287
Joined: Wed Feb 14, 2018 9:21 pm

Re: What is the default lower boundary condition is for WRF?

Post by kwerner » Mon Nov 02, 2020 11:00 pm

Hi,
In reviewing posts, I found this one has not been answered. I first would like to apologize for the oversight. It is never our intention to leave posts unaddressed. As this was so long ago, I first would like to ask if you've been able to get past the problem.
NCAR/MMM

badtanjil
Posts: 3
Joined: Fri Jan 31, 2020 11:06 pm

Re: What is the default lower boundary condition is for WRF?

Post by badtanjil » Mon Nov 30, 2020 9:47 am

Hello,
Thanks for reviewing the post. We could not get past the problem yet. We just want to know what kind of lower boundary condition is used in WRF. We suspect it is free slip plus an inviscid wall but we want to know some details on this.

Thanks.

kwerner
Posts: 2287
Joined: Wed Feb 14, 2018 9:21 pm

Re: What is the default lower boundary condition is for WRF?

Post by kwerner » Tue Dec 01, 2020 6:18 pm

Hi,
This would depend on your isfflx setting. Can you attach your namelist.input file so that we can take a look at the settings? Thanks!
NCAR/MMM

badtanjil
Posts: 3
Joined: Fri Jan 31, 2020 11:06 pm

Re: What is the default lower boundary condition is for WRF?

Post by badtanjil » Fri Dec 18, 2020 9:57 pm

Hello,

Here is my namelist.input file:
[attachment=0]namelist.input[/attachment]

Thanks.
Badrul
Attachments
namelist.input
(5.65 KiB) Downloaded 16 times

kwerner
Posts: 2287
Joined: Wed Feb 14, 2018 9:21 pm

Re: What is the default lower boundary condition is for WRF?

Post by kwerner » Wed Jan 27, 2021 8:21 pm

I once again would like to apologize for the delay in response. I've spoken to our physics specialist who says that it's not recommended to use isfflx=1 with surface and boundary layer physics turned off. However, this may give the same results as isfflx=0. The defaults would be no heat flux and zero drag coefficient. isfflx=1 is designed to interact with the physics using a calculated heat flux and drag or u*, so it would need to be run with a surface layer option, and possibly a land model, to provide those.
NCAR/MMM

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