NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
The information you need is there in the variable information:
short Wind_U(time, lat, lon) ;
Wind_U:long_name = "Wind U Component" ;
Wind_U:units = "m/s" ;
Wind_U:scale_factor = 0.01f ;
Wind_U:valid_range = -100s, 100s ;
Wind_U:missing_value = -9999s ;
Wind_U:_FillValue = -9999s ;
Wind_U:coordinate = "lon lat" ;
So the values are in m/s but need a scale factor of 0.01 applied because it is
stored as a short integer rather than a float. Thus 155 is 1.55 m/s.
As for the ordering, these are in the C convention (opposite of Fortran) 'time'
is the slowest index, whereas 'lon' is stride one. [In the Fortran interface,
the arrays are automatically switched to (lon, lat, time)]
Thus:
Wind_U(time=0, lat=-90, lon=0) = 155 -> 1.55 m/s
Wind_U(time=0, lat=-90, lon=0.5) = 158 -> 1.58 m/s
Wind_U(time=0, lat=-90, lon=1.0) = 161 -> 1.61 m/s
etc.
-- Ted
__________________________________________________________
| Edward Mansell <ted.mansell@xxxxxxxx>
| National Severe Storms Laboratory
|--------------------------------------------------------------
| "The contents of this message are mine personally and
| do not reflect any position of the U.S. Government or NOAA."
|--------------------------------------------------------------
I suggest getting a viewing tool like ncview to peruse the data graphically.
On May 20, 2015, at 9:58 PM, 동희 <gksgg@xxxxxxxxx> wrote:
> Dear NetCDF suppot team
>
>
> Hello
>
> I am DH from Korea.
>
> I am going to use netcdf file soon to get the weather information at my
> company.
>
> But the problem is I am the first one in my company so don't know how to
> interpret the nc file.
>
> (I can just convert to txt file with ncdump, and read the letters...)
>
>
> below is the netcdf file which I should interpret...(it contains global wind
> information)
>
>
> ========================================================================================
>
> netcdf GFS20150520 {
> dimensions:
> lon = 720 ;
> lat = 361 ;
> time = UNLIMITED ; // (57 currently)
> variables:
> float lat(lat) ;
> lat:long_name = "Latitude" ;
> lat:units = "degrees_north" ;
> lat:missing_value = -99999.f ;
> lat:_FillValue = -99999.f ;
> float lon(lon) ;
> lon:long_name = "Longitude" ;
> lon:units = "degrees_east" ;
> lon:missing_value = -99999.f ;
> lon:_FillValue = -99999.f ;
> int time(time) ;
> time:long_name = "forecast time" ;
> time:units = "minutes since 2015-05-20 00:00" ;
> time:standard_name = "time" ;
> time:reference = "UTC" ;
> time:missing_value = -99999 ;
> time:_FillValue = -99999 ;
> short Wind_U(time, lat, lon) ;
> Wind_U:long_name = "Wind U Component" ;
> Wind_U:units = "m/s" ;
> Wind_U:scale_factor = 0.01f ;
> Wind_U:valid_range = -100s, 100s ;
> Wind_U:missing_value = -9999s ;
> Wind_U:_FillValue = -9999s ;
> Wind_U:coordinate = "lon lat" ;
> short Wind_V(time, lat, lon) ;
> Wind_V:long_name = "Wind V Component" ;
> Wind_V:units = "m/s" ;
> Wind_V:scale_factor = 0.01f ;
> Wind_V:valid_range = -100s, 100s ;
> Wind_V:missing_value = -9999s ;
> Wind_V:_FillValue = -9999s ;
> Wind_V:coordinate = "lon lat" ;
>
> // global attributes:
> :title = "Environmental data" ;
> :version = "1.0" ;
> :institution = "ASA" ;
> :Contact = "asa@xxxxxxxxxx" ;
> :source = "NCEP NOAA" ;
> :reference = "Created by DAN_GRIB2NC2 Version 3.0d at 05/20/15 18:14:53" ;
> :default_view = "10 meter Wind U, Wind V " ;
> :netcdf_class = "2" ;
> :netcdf_class_description = "Multi point, static, ..." ;
> :time_var = "time" ;
> :lat_var = "Lat" ;
> :lon_var = "lon" ;
> :view_style = "1" ;
> :Conventions = "CF-1.0" ;
> data:
> lat = -90, -89.5, -89, -88.5, -88, -87.5, -87, -86.5, -86, -85.5, -85,
> -84.5, -84, -83.5, -83, -82.5, -82, -81.5, -81, -80.5, -80, -79.5, -79,
> -78.5, -78, -77.5, -77, -76.5, -76, -75.5, -75, -74.5, -74, -73.5, -73,
>
> .....(oimt).....
>
> lon = 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8,
> 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5,
> 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 20.5, 21, 21.5, 22, 22.5, 23,
> 23.5, 24, 24.5, 25, 25.5, 26, 26.5, 27, 27.5, 28, 28.5, 29, 29.5, 30,
>
> .....(oimt).....
>
> time = 0, 180, 360, 540, 720, 900, 1080, 1260, 1440, 1620, 1800, 1980, 2160,
> 2340, 2520, 2700, 2880, 3060, 3240, 3420, 3600, 3780, 3960, 4140, 4320,
> 4500, 4680, 4860, 5040, 5220, 5400, 5580, 5760, 5940, 6120, 6300, 6480,
> 6660, 6840, 7020, 7200, 7380, 7560, 7740, 7920, 8100, 8280, 8460, 8640,
> 8820, 9000, 9180, 9360, 9540, 9720, 9900, 10080 ;
>
> Wind_U =
> 155, 158, 161, 164, 166, 168, 171, 175, 177, 179, 182, 184, 188, 190, 192,
> 194, 197, 200, 203, 204, 207, 209, 212, 214, 216, 220, 222, 224, 227,
> 229, 230, 233, 235, 237, 239, 241, 245, 247, 249, 251, 253, 255, 256,
>
> .....(oimt).....
>
> Wind_V =
> -310, -309, -308, -307, -306, -304, -303, -301, -300, -298, -297, -295,
> -292, -291, -289, -287, -286, -284, -282, -281, -280, -278, -276, -274,
> -272, -270, -267, -265, -263, -262, -259, -257, -256, -254, -252, -250,
> -248, -246, -244, -241, -238, -236, -234, -232, -230, -228, -226, -223,
>
> .....(oimt)
>
> ========================================================================================
>
>
> For example, at the above file, the first value of Wind_U, 155 is simply
> meaning Wind_U(time, lat, lon)=Wind_U(0, -90, 0) ?
>
> Then what about the second value of Wind_U, 158 ? Is that meaning Wind_U(0,
> -90, 0.5) ? or Wind_U(180, -90, 0) ?
>
> I am not sure this is right and I don't know about the order...
>
>
> Please reply me with brief explanation.
>
> Thank you for reading.
>
>
> Best Regards
>
> DH HAN
>
>
>
> _______________________________________________
> netcdfgroup mailing list
> netcdfgroup@xxxxxxxxxxxxxxxx
> For list information or to unsubscribe, visit:
> http://www.unidata.ucar.edu/mailing_lists/
netcdfgroup archives: