[gradsusr] Customize time axis

[Stefano Materia]

Dear all,
I am facing a very annoying problem which I am not able to get around.

I have netcdf data for the month of January, in which four temperatures
are registered every day: at 8:00am, 11:00am, 2:00pm, 11:00pm. Basically,
I have 124 values per month (31*4) specified at those exact times of the
day, and this is how I want to graph them.

     RefTime =  1980-01-01 06:00:00  Units = days  Calendar = standard
  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss YYYY-MM-DD
hh:mm:ss
  1980-01-01 08:00:00  1980-01-01 11:00:00  1980-01-01 14:00:00 1980-01-01
23:00:00
  1980-01-02 08:00:00  1980-01-02 11:00:00  1980-01-02 14:00:00 1980-01-02
23:00:00
  1980-01-03 08:00:00  1980-01-03 11:00:00  1980-01-03 14:00:00 1980-01-03
23:00:00
  1980-01-04 08:00:00  1980-01-04 11:00:00  1980-01-04 14:00:00 1980-01-04
23:00:00
  ...

When I try to plot this in Grads though, the time axis becomes
disarranged: Grads splits the time steps every three hours

ga-> q file
File 1 :
  Descriptor: tday_jan_daymean_1981-2010.nc
  Binary: tday_jan_daymean_1981-2010.nc
  Type = Gridded
  Xsize = 464  Ysize = 201  Zsize = 1  Tsize = 124  Esize = 1
  Number of Variables = 1
     tn  0  t,y,x  temperature
ga-> set t 1
Time values set: 1980:1:1:8 1980:1:1:8
ga-> set t 2
Time values set: 1980:1:1:11 1980:1:1:11
ga-> set t 3
Time values set: 1980:1:1:14 1980:1:1:14
ga-> set t 4
Time values set: 1980:1:1:17 1980:1:1:17
ga-> set t 5
Time values set: 1980:1:1:20 1980:1:1:20
ga-> set t 6
Time values set: 1980:1:1:20 1980:1:1:23

This is not right, because I need my points to be centered at the time
temperature are registered. Attached, a snapshot of the wrong plot coming
out (for simplicity, I plotted up to the 16th timestep, which should be
Jan 4, but it's not).

I do not even find a way to specify this into the TDEF of a ctl file.

Is anyone able to help me?
Thanks a lot!

-- 
Stefano Materia, PhD
Centro Euro-Mediterraneo sui Cambiamenti Climatici
Viale Aldo Moro, 44 - 40127 Bologna
Tel: +39 051 3782611
Fax: +39 051 3782655


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