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, 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), 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/
(510) 495-8047






On Fri, May 3, 2013 at 2:51 AM, James Ciarlo` <james.ciarlo@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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