is there rule for parent/nested domain grid cell proportion

[omoakinyoola73]

Dear all,
I understand the 1:3 resolution ratio rule when setting up parent and nested domains in WRF. This is usually handled automatically—for example, when using the WRF Domain Wizard to define the bounding boxes. However, I’m currently facing a challenge in determining the appropriate number of grid cells for nested domains. My concern is avoiding excessive grid points that may lead to unnecessary computational cost without significantly improving simulation quality.
Here’s an example of my current domain setup:

• Domain 1: 167 × 115 = 19,205 grid points
• Domain 2: 304 × 259 = 78,736 grid points
• Domain 3: 652 × 352 = 229,504 grid points

I suspect there’s an issue with how I’ve configured the nested domains, but I’m not yet clear on the best practices or guiding principles for choosing optimal grid sizes—especially in terms of balancing resolution and computational efficiency.

I would greatly appreciate any comments, suggestions, or resources that could help clarify this aspect.


Kind regards,
Julius

 

[kwerner]

Hi Julius,

While we don't have any resources that are specific to setting up a domain to save on computational cost, a couple resources that may be helpful are

• This Best Practices page, which, if you click on the namelist.wps variables, it will take you to more detailed descriptions
• Nested Domains presentation - either the video or the .pdf version