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Re: annual averages from non-calendar axis



Hi Will,
You want to define a calendar axis that is equivalent to the axis
your data is generated on, with the NOLEAP attribute, and regrid
with @ASN to that axis, then use regridding with @AVE to an
annual NOLEAP calendar axis.  i.e. say your model data is 1 value per
month.  Your input data might look like this, with the first point, L=1,
corresponding to 1-jan-2000.

  yes? show grid var
      GRID INGRID
   name       axis              # pts   start                end
   VX    LONGITUDE          180mr   21E                  19E(379)
   VY    LATITUDE            90 r   89S                  89N
    normal   Z
   T_IN                    1212 r    1                   1212

  yes?    ! Define monthly calendar time axis; @ASN data to it.
  yes? def axis/t=1-jan-2000:1-dec-2052:1/unit=months/calendar=noleap month_noleap
  yes? let var_month = var[gt=month_noleap@asn]

  yes?    ! Define yearly calendar time axis.  Regrid to get annual averages.
  yes? def axis/t=1-jan-2000:1-dec-2052:12/unit=months/calendar=noleap year_noleap
  yes? let var_year = var_month[gt=year_noleap@ave]

  yes? plot/x=180/y=0 var_year
 
 

This is just an outline.  You will want to think about whether your monthly
data should be centered at the beginning or middle of the months and years,
and so forth.

Ansley Manke
 

Will Lewis wrote:

Greetings Ferret Users,

I have monthly model data which are contained on a no-leapyear, non-calendar
axis, and I would like to create annual averages. I tried following the example
on the ferret website, but I run into the bugaboo of only the @ASN
transformation being allowed between non-calendar and calendar axes (as opposed
to the @AVE, which I need). I tried regridding the data to an artificial,
noleap calendar axis (i.e. defining an axis along the lines of
T="01-JAN-2000":"01-DEC-2100":1/unit=month") but still run into the same error
message when I try to regrid the data from that axis. Any suggestions?

thanks much,
Will

--

___

William Lewis (welewis@students.wisc.edu, will@blue.meteor.wisc.edu)
Department of Atmospheric Sciences / Center for Climatic Research
University of Wisconsin -- Madison

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246
 
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