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Re: [ferret_users] calculating extreme january temperatures



Hein,

See http://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/Grids-Regions/GRIDS#_VPINDEXENTRY_650

There is an "@max" transformation for climatological regridding.

    yes? USE climatological_axes
    yes? CANCEL DATA climatological_axes    ! optional
    yes? LET my_monthly_maxes = temp[GT=monthly_irreg@max]

    - Steve

On 3/13/2013 7:29 AM, Hein Zelle wrote:
Dear Ferret users,

I'm getting stuck with an analysis problem - does anyone know a
solution?  Given an hourly time series (e.g. 10 years), I would like
to calculate the maximum value that occurs in any january month of the
whole time series.  Same for february, march, etcetera.

I can calculate the climatological monthly mean and anomalies without
problems using the climatological_axes.  I can calculate the maximum
temperature in each january month separately by doing

   ! define a monthly_axis for the full 10 year period
   let monthly_max_data = hourly_data[t=monthly_axis@max]

Now I'm stuck.  How do I get the maximum of the individual january
maxima?  I can compute the climatological average january maximum by
using monthly_max_data[gt=month_irreg@mod], but I can't use @mod and
@max at the same time.

I would like to write

   let extreme_max = monthly_max_data[gt=month_irreg@max]

but ferret doesn't like that.

Any hints will be appreciated.
Thanks,

	Hein





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