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Question about running nested ndown with 4 domains

angelarc

New member
Hi,

We are trying to run a nested simulation for four domains and to run ndown.exe as detailed in the instructions available here: Running WRF — WRF Users Guide documentation

The first domain runs smoothly and we get the expected results, then for the second domain:
- We rename wrfinput_d02 to wrfndi_d02
- Add parameter io_form_auxinput2=2 to the namelist.
- Run run ndown.exe for the four domains.
- Delete column one for these parameters e_we, e_sn, dx, dy so they will have the values needed to run domain 2. Also set max_dom = 1 and time_step =16.
- Run wrf.exe

For the third domain, we follow the instructions renaming the outputs and setting the parameters as described in the section Running ndown.exe for Three or More Domains with no issue up until step 5. We have some doubts regarding the setup needed. We are changing parameters grid_id, parent_id, i_parent_start, j_parent_start, parent_grid_ratio, parent_time_step_ratio so they have the values for domains 2, 3, and 4 to run ndown again but we don't know if this should be like this or if we should change the parameters so they have values for domains 3 and 4. Also, if there are any other parameters that we should modify or change back from running ndown for domain 2.
We are attaching two namelists, one is the original one and the other is the modified one we use to run ndown for domain 3.

Thanks for your help!
 

Attachments

  • namelist_for_d03.input
    9 KB · Views: 13
  • namelist.input
    9.1 KB · Views: 10
Last edited:
Hi,
In your namelist.input file for d03,

1) You need to remove io_form_auxinput2 = 2 from the &domains namelist record. You already have it in &time_control (which is the correct location).
2) When you run ndown.exe, max_dom should be set to 2 and should be set up with your original domain 2 in the first column and the original domain 3 in the second column. When you run real.exe, you will then set max_dom = 1, making sure the first column reflects settings for your original d03.
3) You should not need to modify grid_id, parent_id, i/j_parent_start, parent_grid_ratio, or parent_time_step_ratio. You only need to modify e_we, e_sn, time_step, and dx/dy.
 
Hi,

Sorry for the delay in answering, I was on vacation for some time.

I'm going to try your suggestions and will get back to you with the results. I have only one question about what you mention on the second point:

When you run real.exe, you will then set max_dom = 1, making sure the first column reflects settings for your original d03.When you run real.exe, you will then set max_dom = 1, making sure the first column reflects settings for your original d03.

Do you mean wrf.exe?

Thanks in advance.
 
Hi,

I have been able to run a simulation with the changes you suggested:

1) Run real.exe for all the domains (4).
2) Run wrf.exe for the first two domains (d01 & d02).
3) Renamed wrfinput_d03 to wrfndi_d02
4) Run ndown.exe

When running ndown.exe I got the following error (I'm attaching the rsl.error.0000 too):

Input data is acceptable to use: wrfndi_d02
i_parent_start from namelist.input file = 104
i_parent_start from gridded input file = 142
j_parent_start from namelist.input file = 104
j_parent_start from gridded input file = 91
---- ERROR: Nest start locations do not match: namelist.input vs gridded input file
NOTE: 1 namelist vs input data inconsistencies found.
-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE: <stdin> LINE: 1303
NOTE: Please check and reset these options
-------------------------------------------

Another thing that I'm wondering and that I don't know if I'm understanding correctly from what I've read in the documentation. Upon running the first two domains we get two sets of outputs: wrfout_d01* and wrfout_d02*. In order to run ndown.exe for the third domain, should we rename wrfout_d02* outputs as wrfout_d01* outputs?

I'm also attaching two namelists, the ones I used for my tests:
  • namelist_all.input contains the information for all the domains and is the one we used to run the model for the first two domains (d01 & d02).
  • namelist_ndown_d03.input is the namelist I used to run ndown.exe
Is there anything I've missed or something that I need to do in a different way?

Thanks a lot for your help!
 

Attachments

  • rsl.error.0000
    2 KB · Views: 1
  • namelist_ndown_d03.input
    9.1 KB · Views: 6
  • namelist_all.input
    9.1 KB · Views: 5
Last edited:
Hello,
I got the same error message as your latest post, may I ask have you solved this problem yet? Besides that may I ask the author that for the domain 1 and 2, do you mean to run wrf.exe as a normal nesting domain instead of using ndown method to run one by one?
thanks
 
Hi,

I have been able to run a simulation with the changes you suggested:

1) Run real.exe for all the domains (4).
2) Run wrf.exe for the first two domains (d01 & d02).
3) Renamed wrfinput_d03 to wrfndi_d02
4) Run ndown.exe

When running ndown.exe I got the following error (I'm attaching the rsl.error.0000 too):



Another thing that I'm wondering and that I don't know if I'm understanding correctly from what I've read in the documentation. Upon running the first two domains we get two sets of outputs: wrfout_d01* and wrfout_d02*. In order to run ndown.exe for the third domain, should we rename wrfout_d02* outputs as wrfout_d01* outputs?

I'm also attaching two namelists, the ones I used for my tests:
  • namelist_all.input contains the information for all the domains and is the one we used to run the model for the first two domains (d01 & d02).
  • namelist_ndown_d03.input is the namelist I used to run ndown.exe
Is there anything I've missed or something that I need to do in a different way?

Thanks a lot for your help!
Hi,
I encounter the same problem to you, while I solved it via editing the i_parent_start and j_parent_start in namelist from 104 to 142, 104 to 91, it would be moving the third column to the second column of these parameters in your namelist. it works to me, hope do well to you.
 
HI,
@angelarc

I believe @xuzhou12 is correct and that you actually do have to modify i_parent_start and j_parent_start (move them to the appropriate columns) when running ndown.exe for domain 03.

Another thing that I'm wondering and that I don't know if I'm understanding correctly from what I've read in the documentation. Upon running the first two domains we get two sets of outputs: wrfout_d01* and wrfout_d02*. In order to run ndown.exe for the third domain, should we rename wrfout_d02* outputs as wrfout_d01* outputs?
Yes. Because the ndown program relies on very specific file names, it will be looking for the files wrfndi_d02 and wrfout_d01* files. Although the original wrfout_d02 files are for domain 02, the ndown program expects the prefix 'wrfout_d01.' I would recommend copying the original wrfout_d02* (and wrfout_d01*) files somewhere else so you don't overwrite them.
 
Hello,

We have been testing and trying several iterations of tests following your suggestions and they have all worked well.
So thank you very much for your help.
 
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