[ferret_users] seasonal average...

[Seontae Kim <stkim423@xxxxxxxxx>]

Dear Ferreters...

I am trying to a DJF average of a nino index.


def axis/t=15-jan-1950:15-dec-2009:1/unit=month t1
def grid/t=t1 time
file/var="nino4,nino3"/grid=time nino4_nino3.dat

list nino4
             VARIABLE : NINO3
             FILENAME : nino4_nino3.dat
             SUBSET   : 720 points (TIME)
.
.
.
 14-NOV-2002 / 635:  1.528
 15-DEC-2002 / 636:  1.499
 14-JAN-2003 / 637:  0.937
 14-FEB-2003 / 638:  0.538
 16-MAR-2003 / 639:  0.388

.
.
.
list nino3[t=15-dec-2002:15-feb-2003@ave]
             VARIABLE : NINO3
             FILENAME : nino4_nino3.dat
             TIME     : 15-DEC-2002 00:00 to 15-FEB-2003 00:00 (averaged)
          0.9760
list nino3[l=636:638@ave]
             VARIABLE : NINO3
             FILENAME : nino4_nino3.dat
             TIME     : 30-NOV-2002 04:43 to 01-MAR-2003 12:11 (averaged)
          0.9911

====
I expected that I have a same value for "nino3[t=15-dec-2002:15-feb-2003@ave]" and "nino3[l=636:638@ave]" but they are different. 
Could you guys please give any comment on it ?

Thanks 

-Seontae-