This looks to be (at least mostly) a CF-compliant file. So you can learn
about what all those attribute mean here:
http://cfconventions.org/
-Chris
On Thu, May 21, 2015 at 8:01 AM, Ted Mansell <ted.mansell@xxxxxxxx> wrote:
> 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/
>
>
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--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
Chris.Barker@xxxxxxxx
