Hi Francois,
When you define the variables for centering, give the variable
definitions a time range. When using linear regridding instead of
modulo regridding, Ferret tries to regrid to the time range of the
modulo axis, which is 16-jan-0000 to 16-dec-0000 (do "show axis
month_reg" to see this). Since your time data in the range 1957 to 2002
doesn't overlap with the year 0000, there is no result. To regrid a
time series variable to a modulo axis and have it apply to the time
range of the variable,
let divc = div[gt=month_reg,t="01-SEP-1957 12:00":"01-AUG-2002
12:00"]
Modulo time axes are defined to have a time in year 0000 or 0001 for
convenience, but this is a case where this choice causes some
confusion. I believe this will solve your problem.
Ansley
DELCLAUX Francois wrote:
Hi, ferret users,
I would like to create a monthly climatology using modulo regridding.
As my variable is defined on the 1rst of each month, I have to center
it in the middle of the month using interpolation regriding first.
So, as described is the documentation (p74 on ferret 4.4 user guide),
here are the different steps:
1) the variable:
div Divergence 1:144 1:73
1:2
1:540
s**-1 on grid GNL1 with -0.00004415594 & -32767 for
missing
data
X=1.2W(-1.2):1.2W Y=91.2S:91.2N Z=-125:1375
2) the grid:
yes? show g/t gnl1
GRID GNL1
name axis # pts start end
LONGITUDE LONGITUDE 144mr 0E 2.5W
LATITUDE LATITUDE 73 r 90S 90N
LEVELIST HEIGHT (millib 2 r- 250 1000
TIME TIME 540 i 01-SEP-1957 12:00 01-AUG-2002
12:00
L T TBOX TBOXLO TSTEP
(hours)
1> 01-SEP-1957 12:00:00 720 17-AUG-1957 12:00:00
505500
2> 01-OCT-1957 12:00:00 732 16-SEP-1957 12:00:00
506220
3> 01-NOV-1957 12:00:00 732 17-OCT-1957 00:00:00
506964
etc...
3) direct modulo regriding on div variable
let divclim1=div[gt=month_reg@mod]
4) centering div variable by interpolation regridding on month_reg
let divc = div[gt=month_reg]
5) modulo regridding
let divclim2 = divc[gt=month_reg@mod]
Now, when I list divclim1, divc and divclim2 on 1960-1961 period, I
get
the following
results:
yes? list/i=10/j=10/k=1/T="1-jan-1960":"1-dec-1961" divclim1,
divc,divclim2
DATA SET: ./atm_era40.nc
TIME: 01-JAN-1960 00:00 to 01-DEC-1961 00:00
LONGITUDE: 22.5E
LATITUDE: 67.5S
HEIGHT (millibars): 250
Column 1: DIVCLIM1 is DIV[GT=MONTH_REG@MOD]
Column 2: DIVC is DIV[GT=MONTH_REG]
Column 3: DIVCLIM2 is DIVC[GT=MONTH_REG@MOD]
DIVCLIM1 DIVCDIVCLIM2
17-DEC-1959 / 23520: -3.646 .... ....
16-JAN-1960 / 23521: -2.322 .... ....
15-FEB-1960 / 23522: 2.363 .... ....
17-MAR-1960 / 23523: 1.639 .... ....
16-APR-1960 / 23524: 4.567 .... ....
17-MAY-1960 / 23525: 2.185 .... ....
16-JUN-1960 / 23526: 4.941 .... ....
17-JUL-1960 / 23527: 1.758 .... ....
16-AUG-1960 / 23528: 0.212 .... ....
16-SEP-1960 / 23529: 2.182 .... ....
16-OCT-1960 / 23530: 0.431 .... ....
15-NOV-1960 / 23531: -2.144 .... ....
16-DEC-1960 / 23532: -3.646 .... ....
15-JAN-1961 / 23533: -2.322 .... ....
15-FEB-1961 / 23534: 2.363 .... ....
17-MAR-1961 / 23535: 1.639 .... ....
17-APR-1961 / 23536: 4.567 .... ....
17-MAY-1961 / 23537: 2.185 .... ....
16-JUN-1961 / 23538: 4.941 .... ....
17-JUL-1961 / 23539: 1.758 .... ....
16-AUG-1961 / 23540: 0.212 .... ....
16-SEP-1961 / 23541: 2.182 .... ....
16-OCT-1961 / 23542: 0.431 .... ....
16-NOV-1961 / 23543: -2.144 .... ....
So I can't center my
original
variable using month_reg interpolation regridding.
I trid the example as described in user guide (test_var_centered and
so...)
and it's OK.
So, why does it run in user guide but not with my variables ?
Thank's in advance...
--
Francois DELCLAUX
------------------------------------------------------------
UMR HydroSciences Montpellier
Universite Montpellier II - Place Eugene Bataillon
Case courrier MSE
34095 Montpellier Cedex 5 FRANCE
http://www.hydrosciences.org/
mailto: delclaux@msem.univ-montp2.fr
Tel : (33) (0)4 67 14 90 11 Fax : (33) (0)4 67 14 47 74
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