Dear Izidine,
after you have created a 12-month climatology, you wil have J,
F, ... D (l=1:12)
let pre_monthlycl = precip[d=1,gt=month_reg@mod] ! 12-month
climatology
with the running smoothing (averaging) you will get an average
for JFM, MAM, ... ,OND (l=1:12, but only l=2:10 will exist)
let pre_3monthav = pre_monthlycl[l=@sbx:3] ! running 3-month average
and this will select MAM, JJA and SON (l=1:4, but only l=:2:4
will exist)
save/file=
pre_seasonal_alt.nc
pre_3monthav[l=1:10:3] ! save only DJF,MAM,JJA,SON
Consequently, they will differ.
Here is my demonstration:
yes? let t2mmod=t2m[l=1:12] !this equals to pre_monthlycl
yes? let t2msbx=t2mmod[l=@sbx:3] !~pre_3monthav
yes? let t2m3month=t2msbx[l=1:10:3] !~pre_3monthav[l=1:10:3]
listings:
T2MMOD T2MSBX
1: -3.000 ....
2: -5.500 -4.867
3: -6.100 -4.833
4: -2.900 -3.600
5: -1.800 -2.967
6: -4.200 -1.700
7: 0.900 -1.033
8: 0.200 -0.500
9: -2.600 -1.133
10: -1.000 -1.667
11: -1.400 -1.433
12: -1.900 ....
T2M3MONTH
1: ....
2: -3.600
3: -1.033
4: -1.667
Peter
On Tue, Jun 15, 2010 at 11:58 AM, Izidine
Pinto
<izidinep@xxxxxxxxx>
wrote:
Dear
ferret users
I am comparing two seasonal means of two files
file 1 contains daily data from 1jan1981 to 31dec1999
and file 2 contains daily data only for 'all' DJF for the same period
1> ./daily.ppt.1981.1999.era40.nc
name title
I J K L
PRECIP TOTAL PRECIPITATION RATE 1:127 1:110 1:1
1:6939
2> ./ppt.DJF.daily.1981_1999.era40.nc
(default)
name title
I J K L
PRECIP TOTAL PRECIPITATION RATE 1:127 1:110
1:1 1:1683
let pre_monthlycl = precip[d=1,gt=month_reg@mod] ! 12-month
climatology
let pre_3monthav = pre_monthlycl[l=@sbx:3] ! running
3-month average
save/file=pre_seasonal_alt.nc pre_3monthav[l=1:10:3] ! save
only DJF,MAM,JJA,SON
shade pre_3monthav[l=1] ! DJF average
shade PRECIP[d=2,l=1:1683@ave] ! DJF average
I was expecting to have the same result
Hope someone can help me to understand why the results differs
Thanks in advance
--
I.P.
"In these matters the only certainty is that nothing is certain".
Pliny the Elder (23 AD - 79 AD)