Re: [netcdf-java] Storm tracks as trajectories

Hi Ken,

This is off-topic, but I recommend you also start adding a CF "calendar"
attribute, such as

  time:calendar = "julian";

to files like this.  The current netCDF snapshot distribution supports a
"-t" option that displays times in a human readable ISO-8601 form, so if
you run "ncdump -t" on the netCDF file corresponding to the CDL you've
given, the output for the time variable is:

 time = "2005-08-18 18", "2005-08-19", "2005-08-19 06", "2005-08-19 12", 
    "2005-08-19 18", "2005-08-20", "2005-08-20 06", "2005-08-20 12", 
    "2005-08-20 18", "2005-08-21", "2005-08-21 06", "2005-08-21 12", 
    "2005-08-21 18", "2005-08-22", "2005-08-22 06", "2005-08-22 12", 
    "2005-08-22 18", "2005-08-23", "2005-08-23 06", "2005-08-23 12", 
    "2005-08-23 18", "2005-08-24", "2005-08-24 06", "2005-08-24 12", 
    "2005-08-24 18", "2005-08-25", "2005-08-25 06", "2005-08-25 12", 
    "2005-08-25 18", "2005-08-26", "2005-08-26 06", "2005-08-26 12", 
    "2005-08-26 18", "2005-08-27", "2005-08-21 12", "2005-08-21 18", 
    "2005-08-22", "2005-08-22 06", "2005-08-22 12" ;

instead of

>  time = 53601.75, 53602, 53602.25, 53602.5, 53602.75, 53603, 53603.25,
>     53603.5, 53603.75, 53604, 53604.25, 53604.5, 53604.75, 53605, 53605.25,
>     53605.5, 53605.75, 53606, 53606.25, 53606.5, 53606.75, 53607, 53607.25,
>     53607.5, 53607.75, 53608, 53608.25, 53608.5, 53608.75, 53609, 53609.25,
>     53609.5, 53609.75, 53610, 53604.5, 53604.75, 53605, 53605.25, 53605.5 ;

This is a new capability that still has limitations and probably bugs,
but we plan to include it in the next release.  I would be curious if
the Julian calendar as defined in the CF conventions corresponds to what
you intended with the
 
    time:long_name = "Modified Julian Day" ;

In other words, have we got the dates and times above right?

--Russ

> I'm working on writing tropical storm track data in netCDF.
> I think they should be written as CDM trajectories, but am unsure how to 
> have ToolsUI recognize them as trajectories.
> I've attached below the CDL for a simple set of two storms. What do I 
> need to change to have ToolsUI recognize them as trajectories??
> 
> Thanks in advance-
> -Ken
> 
> netcdf one_file {
> dimensions:
>         storm = 2 ;
>         record = UNLIMITED ; // (39 currently)
> variables:
>         short storm(storm) ;
>         int firstObs(storm) ;
>         short numObs(storm) ;
>         short trajectoryIndex(record) ;
>         float time(record) ;
>                 time:long_name = "Modified Julian Day" ;
>                 time:units = "days since 1858-11-17 00:00:00" ;
>         float lat(record) ;
>                 lat:long_name = "Storm center latitude" ;
>                 lat:units = "degrees_north" ;
>         float lon(record) ;
>                 lon:long_name = "Storm center longitude" ;
>                 lon:units = "degrees_east" ;
>         short wind(record) ;
>                 wind:long_name = "Minimum Central Pressure" ;
>                 wind:units = "mb" ;
>         short pres(record) ;
> 
> // global attributes:
>                 :cdm_datatype = "Trajectory" ;
>                 :trajectoryDimension = "storm" ;
>                 :Conventions = "Unidata Observation Dataset v1.0" ;
> data:
> 
>  storm = 0, 1 ;
> 
>  firstObs = 0, 34 ;
> 
>  numObs = 34, 5 ;
> 
>  trajectoryIndex = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 
> 16,
>     17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 
> 0, 1,
>     2, 3, 4 ;
> 
>  time = 53601.75, 53602, 53602.25, 53602.5, 53602.75, 53603, 53603.25,
>     53603.5, 53603.75, 53604, 53604.25, 53604.5, 53604.75, 53605, 53605.25,
>     53605.5, 53605.75, 53606, 53606.25, 53606.5, 53606.75, 53607, 53607.25,
>     53607.5, 53607.75, 53608, 53608.25, 53608.5, 53608.75, 53609, 53609.25,
>     53609.5, 53609.75, 53610, 53604.5, 53604.75, 53605, 53605.25, 53605.5 ;
> 
>  lat = 13.3, 13.5, 13.6, 13.8, 14, 14.3, 14.9, 15.7, 16.5, 17.2, 17.8, 
> 18.3,
>     18.6, 18.9, 19.2, 19.6, 20, 20.4, 20.9, 21.4, 22, 22.7, 23.3, 23.9, 
> 24.3,
>     24.7, 25, 25.3, 25.6, 25.7, 25.7, 25.6, 25.5, 25.5, 19.4, 19.6, 19.7,
>     19.7, 19.7 ;
> 
>  lon = -96.6, -98.2, -99.8, -101.3, -102.5, -103.7, -104.7, -105.6, -107.1,
>     -108.5, -110, -111.5, -112.3, -113.2, -114.1, -114.9, -115.6, -116.1,
>     -116.7, -117.2, -117.7, -118.4, -119.1, -119.9, -120.7, -121.6, -122.6,
>     -123.6, -124.6, -125.5, -126.5, -127.5, -128.5, -129.4, -94.5, -95,
>     -95.7, -96.7, -97.7 ;
> 
>  wind = 22, 26, 35, 44, 48, 57, 62, 62, 66, 79, 79, 79, 75, 70, 66, 62, 62,
>     57, 57, 57, 48, 40, 35, 31, 26, 22, 22, 22, 22, 22, 22, 22, 22, 22, 26,
>     31, 40, 31, 22 ;
> 
>  pres = 1007, 1006, 1002, 997, 994, 987, 983, 981, 979, 972, 970, 972, 974,
>     976, 981, 983, 985, 986, 987, 990, 994, 998, 1000, 1002, 1003, 1004,
>     1005, 1006, 1007, 1008, 1008, 1009, 1009, 1010, 1006, 1004, 1001, 1002,
>     1005 ;
> }
> 
> -- 
> Ken Knapp
> Remote Sensing and Applications Division
> National Climatic Data Center
> 151 Patton Ave
> Asheville, NC 28801
> 828-271-4339 (voice) 828-271-4328 (fax)
> http://www.ncdc.noaa.gov/
> http://www.ncdc.noaa.gov/oa/rsad/isccpb1/
> 
> _______________________________________________
> netcdf-java mailing list
> netcdf-java@xxxxxxxxxxxxxxxx
> For list information or to unsubscribe, visit: http://www.unidata.ucar.edu/ma
> iling_lists/ 


  • 2008 messages navigation, sorted by:
    1. Thread
    2. Subject
    3. Author
    4. Date
    5. ↑ Table Of Contents
  • Search the netcdf-java archives: