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Re: [ferret_users] climatology



Hi Vidya,
You need to define a mask to exclude the years you wish to leave out, and then compute the climatology.  To make a mask, define a variable containing the time coordinates of your data, and then the mask will be based on that.  See "masking" in the Users Guide, and then "Climatology, creating".

Here's how to make a mask excluding a couple of different years.  The expressions in grave accents are getting the coordinate value at a particular time. You might need to include hours and minutes if appropriate for your time axis.

  let tcoords = t[gt=sst]

  let tmask1994 = if tcoords lt `tcoords[t="1-jan-1994"]` or \
    tcoords GE `tcoords[t="1-jan-1995"]` then 1
  let tmask1997 = if tcoords lt `tcoords[t="1-jan-1997"]` or \
    tcoords GE `tcoords[t="1-jan-1998"]` then 1

  let tmask = tmask1994 * tmask1997
  let masked_sst = sst* tmask

   ! test
   yes? plot/x=180/y=0 sst, masked_sst


You can define as many of these as you need, combining them by multiplication. Now, follow the documentation for computing a climatology.


On 1/16/2011 9:43 PM, vidya pj wrote:
Hi Ferrets,

 How to make climatology of 20 years (1990-2010) SST, excluding some years (1994,1997,2006)?? Please help me!!!

--
Vidya P J,
Senior Research Fellow,
Physical Oceanography Division,
National Institute of Oceanography,
Dona Paula , Goa-403004
Phone : 0832450306.



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