[ferret_users] Climatology over multiple data sets with differing time axes

[Neil Swart <ncswart@xxxxxxx>]

Hi Ferreters,

I'm looking at surface wind stress from 20 models. Each models wind-stress is in a different file, but all have the same name (tauu). Unfortunately, the length, starting point and end point of the time axis is different for each model.

What I want to do is to use the LAST 100 years of monthly output from each model to produce a single, averaged monthly climatology. I can produce the climatologies, using all times for each model, but have not been successful in limiting the calculation to only the last 100 years from each model.

Does anyone have any suggestions on how to best achieve selecting the last 100 years from each model, even though the calendar dates maybe different?

I have tried several things, like defining a new variable, but this fails, since each data set has a different length of time axis:

let ll = l[gt=tauu] 
let lim = ll[l=@max]  
let tauu_ltr = tauu[l=`lim-1200`:`lim`]


Many thanks,
Neil Swart


My jnl script look something like:

use file1.nc
use file2.nc
.
.
.

! Regrid the winds onto the uvic_escm x,y,z

DEFINE GRID/X=GHO1/Y=GHO1/Z=GHO1 comg
let uvg_grd = tauu[Gxyz=comg]*lmask[G=comg]

! Compute climatologies over the last 100 years of the pinctrl runs

use climatological_axes
let uvg_tauu = uvg_grd[gt=month_noleap@asn]

let mean_clim = (uvg_tauu[d=3] + uvg_tauu[d=4] + uvg_tauu[d=5] + uvg_tauu[d=6] + uvg_tauu[d=7] + uvg_tauu[d=8] + uvg_tauu[d=9] + uvg_tauu[d=10]\ 
                + uvg_tauu[d=11] + uvg_tauu[d=12] + uvg_tauu[d=13] + uvg_tauu[d=14] + uvg_tauu[d=15] + uvg_tauu[d=16] + uvg_tauu[d=17] + uvg_tauu[d=18]\
                + uvg_tauu[d=19]*-1 + uvg_tauu[d=20]*-1 + uvg_tauu[d=21]*-1 + uvg_tauu[d=22]*-1 )/20


---------------------------------------------------
Neil Swart

Climate Modelling Group
School of Earth and Ocean Sciences
University of Victoria
Victoria, BC
Canada

http://climate.uvic.ca/