Ndown and multiple nests - Repost from old forum

Discuss the nesting capability within the model itself and any problems you might have run into.

Ndown and multiple nests - Repost from old forum

Postby malonso » Sun Nov 30, 2008 1:25 am

I am trying to run ndown.exe for 4 nested domains that all have d01 as the parent. I have run real.exe for all 5 domains to generate the appropriate wrfinput_d0* and wrfbdy_d0* files in $moad_dataroot/siprd. I then run wrf.exe on d01 only (with max_dom =1), producing wrfout_d01_* files for the entire forecast period. On completing d01, I move the output files to a subdirectory and link them back to $moad_dataroot/wrfprd. I then link the appropriate $moad_dataroot/siprd/wrfinput_d0* into the work directory as wrf_real_input_em.d0*.$starttime ($starttime is of the format YYYY-MM-DD_hh:mm:ss).

My namelist.input is changed back to have max_dom = 5, and specifies domain 1 as the parent for the four other domains. Below is what $moad_dataroot/wrfprd/namelist.input looks like before running ndown.exe:

Code: Select all
 &domains
 TIME_STEP = 150,
 TIME_STEP_FRACT_NUM = 0,
 TIME_STEP_FRACT_DEN = 1,
 max_dom = 5
 s_we = 1,1,1,1,1,
 e_we = 220,49,49,53,53,
 s_sn = 1,1,1,1,1,
 e_sn = 185,49,45,49,53,
 s_vert = 1,1,1,1,1,
 e_vert = 31,31,31,31,31,
 dx = 25000,6250,6250,6250,6250,
 dy = 25000,6250,6250,6250,6250,
 grid_id        = 1,  2,  3,  4,  5,
 parent_id      = 1,  1,  1,  1,  1,
 i_parent_start = 0,  186,  197,  160,  133,
 j_parent_start = 0,  53,  89,  37,  52,
 parent_grid_ratio = 1,  4,  4,  4,  4,
 parent_time_step_ratio = 1,  5,  5,  5,  5,
 FEEDBACK = 0,
 SMOOTH_OPTION = 2


When I run ndown.exe, I only obtain wrfbdy_d02 and wrfinput_d02. No output is generated for the other three nested domains. Are there any other things that should be tweaked to get ndown working for all the nests, not just d02?

I could potentially set up processing to cycle all the nests through as d02, but that would be a bit tedious for my liking.
malonso
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Re: Ndown and multiple nests - Repost from old forum

Postby malonso » Sun Nov 30, 2008 1:25 am

My option:

All of your 4 nested domains have d01 as the parent, you just run four times ndown.exe seperately. It is not necessary to run four domains simultaneously.
and it is different to the nested grid size like 27-9-3-1 km.
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Re: Ndown and multiple nests - Repost from old forum

Postby wrfhelp » Sun Nov 30, 2008 1:25 am

ndown can only be used to go from one domain to another, not subsequent nests.

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Re: Ndown and multiple nests - Repost from old forum

Postby malonso » Sun Nov 30, 2008 1:27 am

So is the only method of running ndown for multiple nests on the same level (i.e. all with d01 as the immediate parent) to cycle each nest domain through as d02 and move the wrfinput and wrfbdy files created by ndown around to prevent them being overwritten?

Something like the following?
Code: Select all
run ndown for d02
mv $workdir/wrfinput_d02 $workdir/d02/
mv $workdir/wrfbdy_d02 $workdir/d02/

edit namelist.input and remove d02 specs, leaving d03 as "d02"

ln -s $siprd/wrfinput_d03 wrf_real_input_em.d02.$starttime

run ndown for pseudo-d02 (really d03)
mv $workdir/wrfinput_d02 $workdir/d03/
mv $workdir/wrfbdy_d02 $workdir/d03/
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Re: Ndown and multiple nests - Repost from old forum

Postby malonso » Sun Nov 30, 2008 1:27 am

Here is how I do it:

Code: Select all
cp ~/WRFV2/run/grid_9_namelist.input namelist.input
./real.exe
cp wrfinput_d01 wrf_real_input_em.d02.1987-10-03_12:00:00
cp ~/WRFV2/run/ndown_9_namelist.input namelist.input
./ndown.exe
mkdir data_ny_27_1987100312
cp wrfout* ny_27_1987100312/
cp wrfinput_d02 wrfinput_d01
cp wrfbdy_d02 wrfbdy_d01
cp ~/WRFV2/run/grid_9_namelist.input namelist.input
./wrf.exe


Let me know if that does not make sense.

Matt
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Re: Ndown and multiple nests - Repost from old forum

Postby malonso » Sun Nov 30, 2008 1:29 am

There's no problem running ndown if I only want a single nest domain (d02). I can also run all 4 subnests as either one-way or two-way nests at the same time as d01 - i.e. running wrf.exe with max_dom = 5, using wrfinput_d0* as created by real.exe.

I can't run ndown.exe and get wrfinput_d03, wrfbdy_d03, wrfinput_d04, wrfbdy_d04, wrfinput_d05 and wrfbdy_d05. I only get wrfinput_d02 and wrfbdy_d02.

wrfhelp wrote:ndown can only be used to go from one domain to another, not subsequent nests.

wrfhelp

Does this mean ndown will only create initial and boundary condition files for d02, even if d03, d04... are defined with d01 as the parent domain (seems like unusual behaviour)? Or does it mean ndown will not create initial and boundary condition files if d03 has d02 as a parent (which does make sense)?

Although I am prepared to run all 5 domains (1 parent and 4 nests) at the same time, I'd prefer to have the ability to run the nests run after the parent. In terms of processing time, it is quicker to run each of the nests separately rather than at the same time. I know this means less information is passed between the nests and the parent (if I was running two-way nests), but it isn't critical for my application. I also want to have the ability to run ndown on a separate machine to the main machine running the parent domain (d01).
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Re: Ndown and multiple nests - Repost from old forum

Postby malonso » Sun Nov 30, 2008 1:29 am

FYI I went with the option of cycling each nest through as a pseudo-"d02" and running ndown.exe, then renaming it as the appropriate domain. The scripting is less than ideal, but it works for the required application. If anyone is interested in the code to run ndown for multiple nests with the same parent, I can make it available...
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Re: Ndown and multiple nests - Repost from old forum

Postby AlC » Tue Jul 28, 2009 7:05 am

I am interested in the code if it is still available.

Thank you,

Alan
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Re: Ndown and multiple nests - Repost from old forum

Postby maria.prodanova » Tue Apr 27, 2010 7:44 am

I am also interested in the code if it is still available.

Thank you in advance.

Maria
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Re: Ndown and multiple nests - Repost from old forum

Postby sarafenech » Sun Jan 27, 2013 1:43 pm

If this is still available I am also interested in the code as I am having some problem with my simulation. Thanks

Sara
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