How to decide which eta levels to use?

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g_vijayan
Posts: 16
Joined: Sat Oct 05, 2019 5:05 am

How to decide which eta levels to use?

Post by g_vijayan » Fri Apr 09, 2021 4:58 am

I am running WRF model with three two-way nested domains of 9,3 an 1km resolutions. I would like to have very high vertical resolution (~ 100m) upto 3 km as I want to study the boundary layer. How do I decide the number of vertical levels to use?
And, how do I decide the eta levels manually? Should it be logarithmic or are there some rules I need to keep in mind while picking the eta levels?

kwerner
Posts: 2335
Joined: Wed Feb 14, 2018 9:21 pm

Re: How to decide which eta levels to use?

Post by kwerner » Fri Apr 16, 2021 10:28 pm

Hi,
I apologize for the delay. I wanted to check with some colleagues to make sure I give you sound advice. We now have a namelist option called "auto_levels_opt." You can read about it in Chapter 5 of the WRF Users' Guide. That can be used for a first-guess. The low-level stretching rate can be set to 1.0 to give a fixed thickness, and once you run real.exe, they should be printed in your log output file, so you can copy those into your namelist. There is also a table with some examples of setting level parameters found in Chapter 4 of the Users' Guide. Hopefully this will get you started. Let me know if you have additional questions.
NCAR/MMM

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