[gradsusr] Customize time axis
Stefano Materia
stefano.materia at cmcc.it
Thu May 29 08:35:37 EDT 2014
Hi Jennifer,
what a shame!
Thank you anyways to clarify this, maybe it could be an idea for Grads 2.2 :)
Best regards,
Stefano
> Ah, I see -- the problem is that your time axis isn't linear. The time
> increment is not constant -- it looks like your delta-T's (in hours) are
> 3, 3, 9, 9, 3, 3, 9, 9? I hate to say this, but GrADS won't handle that
> data file properly. The requirement of a linear time axis for gridded data
> is non-negotiable.
> --Jennifer
>
> On May 28, 2014, at 6:28 PM, Stefano Materia wrote:
>
>>
>> Hi Jennifer, sorry for my delayed reply.
>>
>> Why do you believe I need two axes? I only have one month (January), and
>> I
>> need to plot my 124 values (four per day at 8, 11, 14, 23). I really
>> think
>> I only need the axis for diurnal cycle at those specific times, but I'm
>> not able to build it :)
>>
>> This is how the ncdump output looks like.
>>
>> ncdump -h tday_jan_daymean_1981-2010.nc
>>
>> netcdf tday_jan_daymean_1981-2010 {
>> dimensions:
>> longitude = 464 ;
>> latitude = 201 ;
>> time = UNLIMITED ; // (124 currently)
>> variables:
>> float longitude(longitude) ;
>> longitude:standard_name = "longitude" ;
>> longitude:long_name = "Longitude values" ;
>> longitude:units = "degrees_E" ;
>> longitude:axis = "X" ;
>> float latitude(latitude) ;
>> latitude:standard_name = "latitude" ;
>> latitude:long_name = "Latitude values" ;
>> latitude:units = "degrees_N" ;
>> latitude:axis = "Y" ;
>> double time(time) ;
>> time:standard_name = "time" ;
>> time:long_name = "Time in days" ;
>> time:units = "days since 1980-01-01 08:00:00" ;
>> time:calendar = "standard" ;
>> short tn(time, latitude, longitude) ;
>> tn:standard_name = "air_temperature" ;
>> tn:long_name = "minimum temperature" ;
>> tn:units = "Celsius" ;
>> tn:add_offset = 0.f ;
>> tn:scale_factor = 0.01f ;
>> tn:_FillValue = -9999s ;
>> tn:missing_value = -9999s ;
>>
>> ///
>>
>> and here is the output of the cdo command showinfo:
>>
>> cdo sinfo tday_jan_daymean_1981-2010.nc
>> File format: netCDF
>> -1 : Institut Source Ttype Levels Num Gridsize Num Dtype :
>> Parameter ID
>> 1 : unknown unknown instant 1 1 93264 1 I16 : -1
>> Grid coordinates :
>> 1 : lonlat > size : dim = 93264 nx = 464 ny = 201
>> longitude : first = -40.375 last = 75.375 inc =
>> 0.25 degrees_E
>> latitude : first = 25.375 last = 75.375 inc =
>> 0.25 degrees_N
>> Vertical coordinates :
>> 1 : surface : 0
>> Time coordinate : 124 steps
>> RefTime = 1980-01-01 08:00:00 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
>> ..................................................................................
>>
>> ///
>>
>> Thanks very much for your help.
>>
>> Stefano
>>
>>
>>> It sounds like what you really need are two axes -- a time axis with a
>>> monthly increment, and another axis for the diurnal cycle at hours 8,
>>> 11,
>>> 14, and 23 (E with a size of 4 would be useful for that). You can't
>>> plot
>>> data at 12hourly and monthly increments in the same dimension. You will
>>> probably need a full descriptor to get it right. What does the ncdump
>>> output look like?
>>> --Jennifer
>>>
>>>
>>>
>>> On May 20, 2014, at 1:32 PM, Stefano Materia wrote:
>>>
>>>> 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 08:00:00 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
>>>>
>>>>
>>>> <GradsPlot.png>_______________________________________________
>>>> gradsusr mailing list
>>>> gradsusr at gradsusr.org
>>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>
>>> --
>>> Jennifer M. Adams
>>> Center for Ocean-Land-Atmosphere Studies (COLA)
>>> 111 Research Hall, Mail Stop 2B3
>>> George Mason University
>>> 4400 University Drive
>>> Fairfax, VA 22030
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> gradsusr mailing list
>>> gradsusr at gradsusr.org
>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>
>>
>>
>> --
>> Stefano Materia, PhD
>> Centro Euro-Mediterraneo sui Cambiamenti Climatici
>> Viale Aldo Moro, 44 - 40127 Bologna
>> Tel: +39 051 3782611
>> Fax: +39 051 3782655
>>
>> _______________________________________________
>> gradsusr mailing list
>> gradsusr at gradsusr.org
>> http://gradsusr.org/mailman/listinfo/gradsusr
>
> --
> Jennifer M. Adams
> Center for Ocean-Land-Atmosphere Studies (COLA)
> 111 Research Hall, Mail Stop 2B3
> George Mason University
> 4400 University Drive
> Fairfax, VA 22030
>
>
>
>
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
>
--
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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