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Feedback in namelist.input

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C

chester

New member
Dear wrfhelp,

I need your help.
I ran WRF version 3.7
I would appreciate if you could take a look at the following questions.

1. Case 1

I set feedback in namelist.input file as:

For nested domains,

max_dom = 2,
feedback = 1,

2. Case 2

max_dom = 3,
feedback = 1,

3. Case 3

max_dom = 3,
feedback = 1, 0, 0,

Questions:
1. In Case 1, it is a two – ways, that is: Domain 2 is feedback to parent domain 1.

2. I am not sure about this case, Case 2.

The relationship between domain 1 and domain 2 is two-ways.
It seems to me that the relationship between domain 2 and domain 3 is one way.
That is: There is no feedback from domain 3 to domain 2 (?) – If this is true, then
the results for domain 1 and domain 2 would be the same for Case 1 and Case 2(?).

3. Case 2 and Case 3 are the same (?)

Thanks.

Chester
 
Chester,

In your case 3, the option feedback = 1, 1, 0 is not correct. The correct option is feedback =1 or feedback =0. This means that for multiple nesting case, the feedback between parent and child domains can be either on or off. You cannot set it on for one child domain but set it off for another child domain.

1. In Case 1, it is a two – ways, that is: Domain 2 is feedback to parent domain 1 --- yes, this is correct

2. In Case 2, D02 will feedback to D01 and D03 will feedback to D02

3. In Case 3, feedback = 1, 0, 0, must be changed to either feedback = 1 or feedback = 0. In the former case, case 3 is the same as case 2

Ming Chen
 
Thank you very much for your reply.
I have another question.

Case 4:

max_dom = 3,

How to specify feedback = ? for
Two ways for D01 and D02: D02 will feedback to D01, and
one way for D02 and D03: No feedback from D03 to D02.
 
Chester,
Case 4 seems like a triple-nested run (max_dom=3).
If you want to run into-way nesting mode (i.e., there is feedback between parent-child domains), you should set feedback =1.
If you want to run in one-way nesting mode (i.e., there is no feeeback from child domain to parent domain), you should set feedback =0.
There is no option to allow two-way nesting between D01 and D02 and one-way nesting between D02 and D03.

Ming Chen
 
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