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Using ndown before concurrent nesting



I am also a new WRF user and my case seems to have some similarities with Arty's from this thread (Help & tips using ndown)
I would like to do WRF-LES simulations with 4 nested domains (2 RANS and 2 LES)
Since I will do a sensitivity study only on LES parameters, I would like to :
- run the 2 RANS domains in 1 way concurrent nesting
- interpolate the d02 output to form the d03 boundary and initial conditions
- run the 2 LES domains in 1 way concurrent nesting (starting later than the RANSs)

ndown seemed to be the proper way of interpolating the data from d02 to d03. According to the user guide (One-way Nested Run Using ndown), I should be able to generate wrfinput and wrfbdy file corresponding to my 3rd domain. However, I won't get my 4th domain wrfinput_d04. I don't want to use ndown again between d03 and d04 because I would like to interpolate d04 BC at every d03 time step to perform LES.
Then I have few questions/suggestions :
1- Can I run ndown between d02 and d04 to generate wrfinput_d04 and then run my LES simulation with wrfinput_d03, wrfbdy_d03 and wrfinput_d04 (renamed as d01 and d02) ?
2- Is there another way of generating wrfinput_d04 from wrfout_d02 ?
3- Should I necessarily use UPP utility to do that ? It seems less proper, and it generates additionnal data.

Thank you,

Hi Mathieu,
Unfortunately the ndown program will only allow you to configure one domain at a time. Therefore you would have to run ndown on d03 and then again for d04. It may be possible that you can make some modifications to the ndown code to do what you're seeking, but we don't have another option at this time. As for UPP, I don't have any experience with that application (it is supported by a different lab at NCAR), so you may want to post in their section of the forum to ask if there is a way to use it for this purpose.