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MEMO
FROM: Steven Worley, Data Support Section
SUB:  NCAR ASCII version of ETOPO5 earth surface elevation

The VAX binary compatible ETOPO5 data set from National Geophysical Data 
Center (NGDC), Boulder CO, 
has been converted to ASCII.  This easy to use and portable data set has
the following characteristics:
    - all elevations are given in meters, positive above sealevel and negative
      below
    - the grid resolution is 5 minutes x 5 minutes (long., lat.)   
    - the data are organized in full 360 degree latitude circles beginning 
      at 90N and stepping southward to 89 55.0S; the circle at 90N has
      constant value and the circle at 90S is not given, but a value of 2810
      meters may be assumed
    - along each circle (latitude line) there are 360*12 = 4320  values
    - there are 180*12 = 2160 latitude lines        
    - each logical (tape) record is 120 eight bit bytes long 
    - one logical record contains 20 grid point values, format 20I6
    - 216 logical records (4320 grid points) represent one latitude line of 
      data, e.g. the first 216 logical records are used to reconstruct the      
      elevation at 90N (all constant), the next 216 logical records apply to 
      the elevations at 89 55.0N, and so on.
    - the first value on a lat. line is matched to 0E longitude, and the 
      last value is 359 55.0E (or equivalently 0 5.0W) longitude 

The data set may be obtained in two slightly different forms.  First 
the complete global set in a single file (56 MBytes), and second in 
two hemispheric files (28 MBytes each).  The second is required when 
1600 bpi copies are made, i.e. two tapes are needed.  In the hemispheric files
the equator is present as the last record in the NH and the first record in the SH.

The original ocean depth and land elevation data were compiled by 
Dr. Peter Sloss of NOAA-NGDC, Boulder CO.
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