Anomaly Problem

[Steve Cocks <scocks@xxxxxxxxxxxxxxxxxx>]

Hello,

I am running into problems calculating seasonal anomalies.
Specifically, I created a seasonal climatology for a variable, create an
average for the entire time of record for the same variable, then try to
take the difference:
**********************
use climatological_axes.cdf
def grid/t=seasonal_reg season_old
let tnew =t[g=season_old] - 24*31 ! Move the time axis back 31 days so
will  be centered on Ja, Ap, Jy, Oc -- time units are hours
def axis/from_data/t/name=tseason_new/units=hours/t0=1-jan-0000/modulo
tnew
def grid/t=tseason_new season_new
**********************
set data precip97_01.nc
**********************
let precip_new=precip[d=2,t=1-sep-1998:31-aug-2001] ! create a new time
axis for variable

let avgPrec=precip[d=2,t=1-sep-1998:31-aug-2001@ave]    !create avg of
precip from 1sep98-31aug01

list/x=153w/y=20s precip_new[d=2,gt=season_new@mod, l=4]-avgPrec
_______________________________________________________________
The result I get from Ferret is:

list/x=153w/y=20s precip_new[d=2,gt=season_new@mod, l=4]-avgPrec
 **ERROR: illegal limits: AVGPREC is not in the range T=01-JAN
00:12:24:15-DEC-1901 05:49
          Axis extremes are T=31-DEC-1996 12:00:31-AUG-2001 12:00
list/x=153w/y=20s precip_new[d=2,gt=season_new@mod, l=4]-avgPrec
Command file, command group, or REPEAT execution aborted


I experimented around with the @asn function using stuff I saw from the
mail archives and manual but couldn't get this to work either.  Can
anyone help me with this?  Thanks.


Scocks
TAMU