ABOUT_DRIFTERS is the jdata module of jLab.

 ABOUT_DRIFTERS  Global surface drifter dataset from the Global Drifter Program. 
    DRIFTERS.MAT and DRIFTERS.NC contain the global surface drifter dataset 
    from NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML)
    Global Drifter Program (GDP) Drifter Data Assembly Center, online at
    This is essentially just a reorganized version of the AOML dataset.
    The only substantial difference is that the data is interpolated to a
    uniform six-hourly time grid with no gaps in the time index. All data
    values during gaps greater than 6 hours are flagged with values of INF.
    DRIFTERS.MAT is a Matlab version, and DRIFTERS.NC is a NetCDF version.
    DRIFTERS is distributed as a part of JDATA, a supplement to the 
    software toolbox JLAB, and is available at http://www.jmlilly.net.
    Matlab version
    LOAD DRIFTERS loads the structure DRIFTERS, with the following fields:
        drifters.about     Pointer to this document            
        drifters.id        Drifter ids                  [24928 x 1 array] 
        drifters.buoy      Drifter buoy type            [24928 x 1 array] 
        drifters.num       Date in DATENUM format       {24928 x 1 cell} 
        drifters.lat       Latitudes                    {24928 x 1 cell} 
        drifters.lon       Longitudes                   {24928 x 1 cell} 
        drifters.u         Eastward velocity in cm/s    {24928 x 1 cell}   
        drifters.v         Northward velocity in cm/s   {24928 x 1 cell}   
        drifters.t         Temperature in centigrade    {24928 x 1 cell} 
        drifters.drogue    Drogue presence flag         {24928 x 1 cell}   
        drifters.laterr    Estimated latitude error     {24928 x 1 cell} 
        drifters.lonerr    Estimated longitude error    {24928 x 1 cell} 
        drifters.terr      Estimated temperature error  {24928 x 1 cell} 
    NUM, LAT, LON, U, V, T, and DROGUE are all cell arrays, with one 
    drifter per cell.
    BUOY and DROGUE are metadata information described below.
    LATERR, LONERR, and TERR are error estimates from the original files.
    A number of routines are available in JLAB to work directly with such
    cell arrays, see JCELL.  In particular, CELLPLOT will plot such data.
    After 'load drifters', type 'use drifters' to map the structure fields 
    into named variables in the workspace--id, num, lat, lon, etc.
    To plot the entire drifter dataset, as in the above figure, type 
       load drifters, use drifters, cellplot(380,lon,lat), topoplot
    where 380 specifies the right-hand axis of the plot, chosen to be 
    the longitude of the southern tip of Africa.
    To convert the cell arrays into one long column vector, with a NAN 
    separating each drifter, type 'cell2col(num,lat,lon,u,v,t);'.
    The fields BUOY and DROGUE give metadata information. BUOY is the drifter
    design type according to the following code:
       1=SVP,  2=SVPB, 3=SVPC, 4=SVPBS, 5=SVPW, 6=SVPBW.
    DROGUE is true when the drifter's drogue is estimated to be present, and
    false otherwise. 
    NetCDF version
    The NetCDF version is basically the same as the mat-file version, but
    having all the cell array fields stored as column arrays with 
    separating NaNs, see COL2CELL.
    Use the JLAB routine NCLOAD to load the NetCDF file and convert all the
    NaN-separated columns into cells, i.e. 'ncload drifters'.
    Dataset creation
    The files on which DRIFTERS is based are available for download at 
    For completeness, the m-file ABOUT_DRIFTERS also contains the 
    processing steps used in the creation of DRIFTERS.MAT and DRIFTERS.NC.  
    If you wish to do this yourself, with JLAB on your search path, 
    'about_drifters --create' will recreate DRIFTERS.MAT and DRIFTERS.NC
    by reading in the original downloaded data.  This will take a while.
    As of January 2020, the AOML drifter dataset consists of eight files:
    You'll need to make sure to put the directory containing the files on
    your Matlab search path using ADDPATH, e.g. 'addpath ~/Data/aoml'.
    'about_drifters --f' generates the sample figure shown above.
    Usage: about_drifters
           about_drifters --create     
    This is part of JLAB --- type 'help jlab' for more information
    (C) 2007--2020 J.M. Lilly --- type 'help jlab_license' for details

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