JFM averages.

[Marcelo Barreiro <marcelo@xxxxxxxxxxxxx>]

Hi ferreters,

I am computing JFM averages from monthly data of a time series which spans
45 years (540 months). 
I did it in two different ways:

(1st)
define axis/edges/t="16-jan-1950:12":"16-dec-1994:12"/npoints=`45*4` tsea
let my_var_seas = my_var[gt=tsea@ave]
let/quiet my_var_JFM = my_var_seas[l=1:180:4]
 
(2nd)
let/quiet my_var_J = my_var[l=1:540:12]
let/quiet my_var_F = my_var[l=2:540:12]
let/quiet my_var_M = my_var[l=3:540:12]
let/quiet my_var_JFM= (my_var_J + my_var_F + my_var_M)/3

Results of my_var_JFM are similar but not equal and in cases the
correlation between the results of different methods is as low as 0.90.

Does anyone know which way is the best?
Thanks!

Marcelo


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Marcelo Barreiro
Dept. of Oceanography, Physical Section
College of Geosciences and Maritime Studies
Texas A&M University
College Station, TX 77843-3146
Phone: (979) 845-8216
Email: marcelo@ocean.tamu.edu
URL: http://www-ocean.tamu.edu/~marcelo/
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