[Wrf-users] Wrf-users Digest, Vol 143, Issue 22

[jagan TNAU]

Hello Juliet,

As Mike pointed out you can run the simulation without nest. As your input
is 83 KM resolution your domain can be 3-5 folds resolution of the input
data. Since your input is 83 KM you can run with a domain of size 16.6 KM.
You need not run a new for that. As Mike suggested you can run use 16 KM as
domain and run sensitivity experiment to check your outputs are fine



On Tue, Jul 26, 2016 at 1:21 AM, <wrf-users-request at ucar.edu> wrote:

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> Today's Topics:
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>    1. Re: Is it a must to run wrf with a nest (Mike Dvorak)
>    2. Re: Is it a must to run wrf with a nest (afwande juliet)
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> Message: 1
> Date: Mon, 25 Jul 2016 10:47:37 -0500
> From: Mike Dvorak <mike at sailtactics.com>
> Subject: Re: [Wrf-users] Is it a must to run wrf with a nest
> To: wrf-users at ucar.edu
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> Message: 2
> Date: Mon, 25 Jul 2016 22:34:47 +0300
> From: afwande juliet <afwandej965 at gmail.com>
> Subject: Re: [Wrf-users] Is it a must to run wrf with a nest
> To: Mike Dvorak <mike at sailtactics.com>
> Cc: wrf users group <wrf-users at ucar.edu>
> Message-ID:
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> Thanks guys for this useful piece of information. I have 32cpus and 2
> nodes. I am testing many convective schemes over East Africa. If I got you
> right, if my data is at 83km, then the outer nest should be between 5-3
> times less, that means the inner nest will be about 9.33km if ratio 1.3 is
> considered. My confusion is 9km is too expensive to run than 28 or 32km.
> For my case do I set the domain such that the inner nest is 28km or what??.
> This is because the if outer nest is 32km then inner must be 10.5km there
> about which is too expensive.
>
>
> On Jul 25, 2016 9:05 PM, "Mike Dvorak" <mike at sailtactics.com> wrote:
>
> > Hi there,
> >
> > You typically don't have to start with your first domain at the same
> > resolution of the input dataset. I would start out with something on the
> > order of 3 to 5 times smaller in delta x and y. So if your input data is
> 83
> > km, your WRF parent (first) domain could be roughly between 28 to 16 km.
> >
> > You might run some sensitivity experiments to see how well the model
> > matches observations by going directly to 16 km. The results might be
> good
> > enough for your purposes and would save you having to run that extra
> > domain. Removing parent domains does *not* often make a huge difference
> > in wallclock time because the inner nests run multiple timesteps for each
> > time the parent domains runs.
> >
> > Best of luck with your experiment.
> >
> > Cheers,
> > Mike
> >
> > On 07/24/2016 09:34 AM, afwande juliet wrote:
> >
> > Dear users
> > I am running wrf using era interim which is at 83km resolution. I am
> > downscaling to about 16KM nest
> > It's very slow. I even deactivated the parent domain so that I only get
> > output from nest to reduce runtime but still takes 84hrs to run 3months
> > simulation which is too slow.
> >
> > What would be the danger if I run without nest to reduce runtime
> >
> > Would there be any mismatch between the driving data and the model
> >
> >
> > _______________________________________________
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> >
> > --
> > [image: Sail Tactics logo]
> > Mike Dvorak, PhD
> > Founder
> > Sail Tactics, LLC
> > Corpus Christi, TX
> > +1 650-454-5243
> > http://sailtactics.com
> >
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> End of Wrf-users Digest, Vol 143, Issue 22
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-- 
With regards

Dr.R.Jagannathan
Professor & Former Dean
Tamil Nadu Agricultural University
Coimbatore - 641 003 India

PHONE:  Mob: +91 94438 89891

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