Your original data must be on a time axis that uses a calendar other than the default Gregorian calendar. See "calendar" in the Users Guide. To regrid this to a climatological axis, you must either regrid your original data to a Gregorian time axis of the same length as the original axis (using @LIN, @ASN or @NRST interpolation), or define a climatological time axis that uses the same calendar as the original axis. I would suggest that you create your own climatological axis to match the calendar of your data, since that would involve fewer regridding operations.
Here is a previous entry which talks about this issue and has an example showing how to define a climatological axis for a different calendar.
http://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2002/msg00224.html
That example did a regularly-spaced calendar axis. The command below will define a calendar axis with boundaries on the month boundaries, using /EDGES to show we're using the start and end day of each month in the definition. I start this at the end of year 0000 so that the first point lies in the middle of January, and so on. SHOW AXIS shows some of the details, and a LIST command shows the coordinates and the box sizes and upper and lower bounds. ( I did an example where I specified the calendar was Julian, so the list output would be a bit different if your calendar is something else.) Note that we could get the day-of-year for the first of each month from the function with the function TAX_JDAY, but since it's just this list of days I typed them in.
yes? define axis/t/cal=`thetao,return=calendar`/t0=31-dec-0000/units=days/edges month_clim = {1,32,60,91,121,152,182,213,244,274,305,335,366}
yes? show axis month_clim
name axis # pts start end
MONTH_CLIM TIME 12 i 16-JAN 12:00 16-DEC 12:00
T0 = 31-DEC-0000
CALENDAR = JULIAN
Axis span (to cell edges) = 365
yes? list t[gt=month_clim], tbox[gt=month_clim], tboxlo[gt=month_clim], tboxhi[gt=month_clim]
TIME: 01-JAN 00:00 to 01-JAN-0002 00:00 JULIAN
Column 1: T is T (axis MONTH_CLIM)
Column 2: TBOX is TBOX (axis MONTH_CLIM)
Column 3: TBOXLO is TBOXLO (axis MONTH_CLIM)
Column 4: TBOXHI is TBOXHI (axis MONTH_CLIM)
T TBOX TBOXLO TBOXHI
16-JAN 12 / 1: 16.5 31.00 1.0 32.0
15-FEB 00 / 2: 46.0 28.00 32.0 60.0
16-MAR 12 / 3: 75.5 31.00 60.0 91.0
16-APR 00 / 4: 106.0 30.00 91.0 121.0
16-MAY 12 / 5: 136.5 31.00 121.0 152.0
16-JUN 00 / 6: 167.0 30.00 152.0 182.0
16-JUL 12 / 7: 197.5 31.00 182.0 213.0
16-AUG 12 / 8: 228.5 31.00 213.0 244.0
16-SEP 00 / 9: 259.0 30.00 244.0 274.0
16-OCT 12 / 10: 289.5 31.00 274.0 305.0
16-NOV 00 / 11: 320.0 30.00 305.0 335.0
16-DEC 12 / 12: 350.5 31.00 335.0 366.0
Now you could regrid with @MOD to the new axis we've just defined.
liulin wrote:
Dear all,I want to calculate the climatological temperature from monthly averaged data. But after I input the below _expression_, Ferret tell me the error is found. The detailed infor is listed below and I do not know why this infor appears? Please help me. Thank you!-----------------------------------use climatological_axes
*** NOTE: regarding d:\Program Files\TMAP\go\climatological_axes.cdf ...
*** NOTE: Climatological axes SEASONAL_REG, MONTH_REG, and MONTH_IRREG defined
cancel data climatological_axeslet t_clima=thetao[gt=month_irreg@mod]cont/l=1 t_clima
**ERROR: regridding: only @ASN, @LIN, or @NRST regridding between calendar type
s: NOLEAP, GREGORIAN
Command file, command group, or REPEAT execution aborted----------------------------Best RegardLiulin
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The First Institute of Oceanography
State Oceanic Administration
P. R. China
No. 6 Xian-Xia-Ling Road, Qingdao 266061
Fax: 86-532-88967403~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
