[RegCNET] RegCM Ensemble run

Travis O'Brien travis.obrien at gmail.com
Fri May 3 16:16:17 CEST 2013


Hi James,

The ensemble_run flag is one of the parameters that activates the
ensembling system. This is a relatively new feature that is described in
the latest version of the RegCM
UserGuide<http://gforge.ictp.it/gf/download/docmanfileversion/54/973/UserGuide.pdf>,
Section 6.1.7.

When the ensembling system is activated, one or more of the boundary
condition fields are perturbed by a small fraction each time they are read
in.  For example, the following settings would use the ensembling strategy
of O'Brien et al. (2011) <http://dx.doi.org/10.1007/s00382-010-0900-5>,
which is the main reference that describes the details of the ensembling
method:

&globdatparam

ensemble_run = .true.

/

&perturbparam

lperturb_q = .true.

perturb_frac_q = 0.001d0

/


With these settings turned on, each time you run regcm, the output will be
slightly different.  So to create an ensemble of simulations, you might run
RegCM five times, and each time change the parameter dirout to output.1,
output.2, output.3, output.4, output.5, etc.

I hope this helps, and please let me know if I can clarify anything.

Kind Regards,
-Travis-

-- 
Travis O'Brien
Lawrence Berkeley National Lab
http://esd.lbl.gov/about/staff/travisobrien/<http://esd.lbl.gov/about/staff/travisobrien/index.html>
(510) 495-8047






On Fri, May 3, 2013 at 2:51 AM, James Ciarlo` <james.ciarlo at physics.org>wrote:

> Dear RegCNET,
>
> I am interested in running an ensemble expleriment with RegCM4. My
> intention was to choose different settings for the different simulations.
>
> I have noticed the setting: ensemble_run = .false.,  in the globdatparam.
> This obviously needs to be set to true, but since I have never done an
> ensemble run before with RegCM4 I was wondering if there was anything I
> needed to know.
>
> Regards,
> James
>
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> RegCNET at lists.ictp.it
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