Re: modulo regridding

[DELCLAUX Francois <francois.delclaux@xxxxxxxxxxxxxxxxxxx>]

Hi Ansley and Jaison,


I tried what you suggested, and found a curious result :

! defining my variable div on a given period (3 years) and a given (x,y,z)
point
let DIV = 10E6*D[D=1, K=1, I=10, J=10, t=1-jan-1958:1-dec-1962]

! defining my own axis
yes? define axis/modulo/t=1-jan-0001:1-dec-0001:`365.2425/12`/units=days
m_reg
 !-> define axis/modulo/t=1-jan-0001:1-dec-0001:30.437/units=days m_reg

! modulo regridding using climatological_axes.cdf
yes? let divc1=DIV[GT=MONTH_REG@MOD]
yes? let divc2=DIV[GT=MONTH_irREG@MOD]

! modulo regridding using
m_reg axis
yes? let divc3=DIV[GT=M_REG@MOD]

! comparing divc1, divc2 and divc3:
yes? list divc1            
             VARIABLE : DIV[GT=MONTH_REG@MOD]
             SUBSET   : 12 points (TIME)
             LONGITUDE: 22.5E
             LATITUDE : 67.5S
             HEIGHT (millibars): 250
                     22.5E 
                     10
 16-JAN      /  1:   1.34
 15-FEB      /  2:   3.47
 17-MAR      /  3:  -2.24
 16-APR      /  4:  -1.79
 16-MAY      /  5:  -5.57
 16-JUN      /  6:  10.33
 16-JUL      /  7:  -4.02
 16-AUG      /  8:  -3.02
 15-SEP      /  9:   1.30
 16-OCT      / 10: -11.34
 15-NOV      / 11:   3.17
 16-DEC      / 12:   1.02
yes? list divc2
             VARIABLE : DIV[GT=MONTH_IRREG@MOD]
             SUBSET   : 12 points (TIME)
             LONGITUDE: 22.5E
             LATITUDE : 67.5S
             HEIGHT (millibars): 250
                        22.5E 
                        10
 16-JAN      12 /  1:   1.34
 15-FEB      02 /  2:   1.56
 15-MAR      17 /  3:   5.39
 15-APR      05 /  4:  -2.24
 15-MAY      17 /  5:  -1.79
 15-JUN      05 /  6:  -5.57
 15-JUL      17 /  7:  10.33
 15-AUG      17 /  8:  -2.20
 15-SEP      05 /  9:  -2.22
 15-OCT      17 / 10:  -0.20
 15-NOV      05 / 11:  -0.51
 15-DEC      17 / 12:   5.99
yes? list divc3
             VARIABLE : DIV[GT=M_REG@MOD]
             SUBSET   : 12 points (TIME)
             LONGITUDE: 22.5E
             LATITUDE : 67.5S
             HEIGHT (millibars): 250
                     22.5E 
                     10
 01-JAN      /  1:   1.34
 31-JAN      /  2:   1.56
 02-MAR      /  3:   5.39
 02-APR      /  4:  -2.24
 02-MAY      /  5:  -1.79
 02-JUN      /  6:  -5.57
 02-JUL      /  7:  10.33
 02-AUG      /  8:  -2.20
 01-SEP      /  9:  -2.22
 01-OCT      / 10:  -0.20
 01-NOV      / 11:  -0.51
 01-DEC      / 12:   5.99

Finaly, results from
m_reg and month_irreg are identical, but:
- for m_reg , variable is set at the beginning
of the month. 
- for month_irreg, values are set at the mid month.

I am not sure to have understood everything concerning modulo regridding,
but the best solution is to define myself the axis I want to regrid on.

Thanks a lot for your contributions.

François Delclaux