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Re: [ferret_users] Ensemble realization analysis

Hi Patrick,

I can reproduce your finding. I GUESS, the i/j-average of the difference between both the experiments is pretty small, even if there are significant differences in some areas. The average runs over 10^4 points. The quantities are of the order 200, the difference is less than +/-10.

Hence it may be that you see simply the limited accuracy of ferret.

I do not know nothing about the experiments, but may it be that some procedure has been applied to
keep the average values fixed?


Brockmann Patrick wrote:
Hi all,

Sorry for the uncompleted previous message.

When you analyze ensemble realizations
(read http://cmip-pcmdi.llnl.gov/cmip5/docs/cmip5_data_reference_syntax.pdf
Ensemble menber paragraph), you would like to work with
a variable over its realizations seen as a nth dimension and then apply on it power of ferret transformations.

Unfortunatelly, there are only 4 dimensions in ferret.
But sometimes, you also may have the chance that the variable you analyze
has 3 dimensions and has a XZT shape.

I have imagined to use the ZCAT function to concat the XYT variable over the Z dimension and then get a XYZT variable with the Z dimension representing a realization dimension.

It seems to work since for one time step I can shade a difference but when I plot a time evolution I get the same plot from the 2 realizations. That is not correct.

Try the attached script if interested.

Any share of experience on this topic is welcome. The challenge of course is not
to physically save files.


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