[MITgcm-support] query ?

[Martin Losch]

Hi there,
I repeat: the plotting routines are really only an example and at most 
a starting point for your own set of plotting routines.

deltaTclock/deltaTtracer:
I don't think that having different values for deltaTtracer and 
deltaTclock is a good idea. deltaTclock is the "real" time step in the 
model: based on deltaTclock, forcing fields are loaded and output is 
written, etc. Having a different deltaTtracer means that you use a 
different timestep for your tracer equations than for your forcing 
fields, something you probably do not want. [In the case of deltaTmom 
and deltaTtracer this is the desired behavior (for spin-up integrations 
only), in order to speed-up the equilibrations times for for temparture 
and salinity distribution in the deep ocean. Have a look at the 
relevant papers (Bryan 1984, JPO, and more recently Danabasoglu 2004, 
Ocean Modelling, etc.) to understand how that works.]

I personally would make sure that for asynchronous time stepping 
deltaTclock=deltaTtracer and for synchonous timestepping 
deltaTclock=deltaT (by not setting deltaTclock in data!!).

Also, as written in the data file of global_ocean.90x40x15, I recommend 
setting deltaTfreesurf=deltaTtracer, if you use an model version > 
checkpoint45.

Hope that helps,
Martin

On Jun 15, 2005, at 1:07 PM, Amitabh Mitra wrote:

>   
>
>  Dear Sir,
>
>  I have run the global_ocean.90x40x15 experiment for
>
>  one year with a resolution of 1x1.
>
>  In the 'data' file I am putting the value for
>
>  deltaTtracer=800.  and  deltaTClock=172800.
>
>  While plotting the output for the last iteration (180)
>
>  I am changing the line no. 4 in  mit_timesteps.m  as 
>
>  deltat = mit_getparm('D:\MITrun\data','deltaTClock');
>
>  i.e. putting  'deltaTClock' in place of 'deltaTtracer',
>
>  (to get proper headings in the plot).
>
>  Is this change logical and valid ? Will the vast difference
>
>  between the two timings have any effect on the model output ?
>
>  Thanking You,
>
>  With regards,
>
>  Amitabh Mitra
>
>
>
>
>
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