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Re: Monthly Data and Descriptor Files
Hi Robin,
I think I remember you being savvy enough to change the axes in your NetCDF file. I
would. I would use the Ferret defined unit "month" which is 365.2425/12. Change
the time axis in each of your NetCDF files. Although this unit of time measurement
will still cause some wandering between the 14th and 17th of the month, you will
never get a time coordinate as far out as the 23rd. Then, in your descriptor file,
set D_TIME_UNIT = 2629746 (This is the number of seconds in (365.2425 days)/12.)
and set the appropriate S_START and S_END in each of the STEPFILE_RECORDS, i.e.
15-JUL-1996 is about 101 months from D_T0TIME = '15-JAN-1988 00:00:00', so the
first S_START = 101, S_END = 106.
Good Luck,
Joe McLean
-----------------------------------------------------------------
Robin Kovach wrote:
> Hello,
>
> I have monthly averaged data for multiple years and I am currently
> using descriptor files so that I can link multiple files together.
>
> So on LAS, the GUI shows selections for 15-Jul-1996, 15-Aug-1996 and
> so on. But when the plot comes up the date on the plot for July 15 1996
> shows up as July 23, 1996. I realize this is the actual time since I
> am computing from 1988 and not taking into accound leap years and
> specific number of days in each month.
>
> But I would like this date on the plot to be exactly the middle of
> each month.
>
> However in using the descriptor files, I need a constant time step. Is
> there any way around this? I"ve attached some useful info below.
>
> Thanks!!!
>
> LAS site : http://mohawk.gsfc.nasa.gov/las
>
> Data Set : POSEIDON_PACIFIC_2D
>
> Right now my data files are:
> 1996_2d.001 TIME = 3126, 3156.5, 3187, 3217.5, 3248, 3278.5
> 1997_2d.001 TIME = 3309, 3339.5, 3370, 3400.5, 3431, 3461.5, 3492, 3522.5,
> 3553, 3583.5, 3614, 3644.5 ;
> 1998_2d.001 TIME = 3675, 3705.5, 3736, 3766.5, 3797, 3827.5, 3858, 3888.5,
> 3919, 3949.5, 3980, 4010.5 ;
>
> where the time parameters are:
> TIME:TIME_origin = "01-JAN-1988 00:00:00" ;
> TIME:units = "days since 1988-01-01 00:00:00" ;
>
> The descriptor file is:
>
> ********************************************************************************
> * DESCRIPTOR FILE
> *
> * to string together multiple files
> *
>
> ********************************************************************************
> $FORMAT_RECORD
> D_TYPE = ' MC',
> D_FORMAT = ' 1A',
> $END
> $BACKGROUND_RECORD
> D_TITLE = 'POSEIDON PACIFIC 2D',
> D_T0TIME = '01-JAN-1988 00:00:00',
> D_TIME_UNIT = 86400
> D_TIME_MODULO = .false.,
> $END
> $MESSAGE_RECORD
> D_MESSAGE = ' ',
> D_ALERT_ON_OPEN = F,
> D_ALERT_ON_OUTPUT = F,
> $END
> **************************************************
> $EXTRA_RECORD
> $END
>
> $STEPFILE_RECORD
> S_FILENAME = '/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/1996_2d.001',
> S_AUX_SET_NUM = 0,
> S_START = 3126.0,
> S_END = 3278.5,
> S_DELTA = 30.5,
> S_NUM_OF_FILES = 1,
> S_REGVARFLAG = ' ',
> $END
> $STEPFILE_RECORD
> S_FILENAME = '/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/1997_2d.001',
> S_AUX_SET_NUM = 0,
> S_START = 3309.0,
> S_END = 3644.5,
> S_DELTA = 30.5,
> S_NUM_OF_FILES = 1,
> S_REGVARFLAG = ' ',
> $END
> $STEPFILE_RECORD
> S_FILENAME = '/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/1998_2d.001',
> S_AUX_SET_NUM = 0,
> S_START = 3675.0,
> S_END = 4010.5,
> S_DELTA = 30.5,
> S_NUM_OF_FILES = 1,
> S_REGVARFLAG = ' ',
> $END
>
>
> **************************************************
> $STEPFILE_RECORD
> S_FILENAME = '**END OF STEPFILES**'
> $END
> **************************************************
>
> POSEIDON_PACIFIC_2D.xml File
> <datasets>
> <POSEIDON_Pacific_2d_nc name="POSEIDON Pacific 2D"
> doc="doc/POSEIDON_Pacific_Model.html">
> <variables>
> <surfaceheight name="Surface Height" units="meters"
> url="file:/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/POSEIDON_PACIFIC_2d#surfaceheight
> ">
> <link match="/lasdata/grids/POSEIDON_Pacific_2d_nc_grid"/>
> </surfaceheight>
> <zonalwindstress name="Zonal Wind Stress" units="m^2/s^2"
> url="file:/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/POSEIDON_PACIFIC_2d#zonalwindstre
> ss">
> <link match="/lasdata/grids/POSEIDON_Pacific_2d_nc_grid"/>
> </zonalwindstress>
> <meridionalwindstress name="Meridional Wind Stress" units="m^2/s^2"
> url="file:/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/POSEIDON_PACIFIC_2d#meridionalwin
> dstress">
> <link match="/lasdata/grids/POSEIDON_Pacific_2d_nc_grid"/>
> </meridionalwindstress>
> <netsurfaceheatflux name="Net Surface Heat Flux" units="W/m^2"
> url="file:/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/POSEIDON_PACIFIC_2d#netsurfacehea
> tflux">
> <link match="/lasdata/grids/POSEIDON_Pacific_2d_nc_grid"/>
> </netsurfaceheatflux>
> <downwardshortwaveflux name="Downward Shortwave Flux" units="W/m^2"
> url="file:/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/POSEIDON_PACIFIC_2d#downwardshort
> waveflux">
> <link match="/lasdata/grids/POSEIDON_Pacific_2d_nc_grid"/>
> </downwardshortwaveflux>
> <evapminusprecip name="Evap - Precip" units="10-5 mm/s"
> url="file:/obs/NSIPP/MODEL/POSEIDON/PACIFIC/2D/POSEIDON_PACIFIC_2d#evapminusprec
> ip">
> <link match="/lasdata/grids/POSEIDON_Pacific_2d_nc_grid"/>
> </evapminusprecip>
> </variables>
> </POSEIDON_Pacific_2d_nc>
> </datasets>
> <grids>
> <POSEIDON_Pacific_2d_nc_grid>
> <link match="/lasdata/axes/POSEIDON_Pacific_2d_nc_LON"/>
> <link match="/lasdata/axes/POSEIDON_Pacific_2d_nc_LAT"/>
> <link match="/lasdata/axes/POSEIDON_Pacific_2d_nc_TIME"/>
> </POSEIDON_Pacific_2d_nc_grid>
> </grids>
> <axes>
> <POSEIDON_Pacific_2d_nc_LON type="x" units="degrees_east">
> <arange start="119.0" step="1" size="173"/>
> </POSEIDON_Pacific_2d_nc_LON>
> <POSEIDON_Pacific_2d_nc_LAT type="y" units="degrees_north">
> <arange start="-45.0" step="1" size="112"/>
> </POSEIDON_Pacific_2d_nc_LAT>
> <POSEIDON_Pacific_2d_nc_TIME type="t" units="month">
> <arange start="1996-7-15" step="1" size="30"/>
> </POSEIDON_Pacific_2d_nc_TIME>
> </axes>
>
>
--
Joseph McLean
NOAA/PMEL/TMAP
(206)526-4286
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