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Expanded Description
Topic Description
Name
seabeam
Synopsis
/infobank/programs/bat/seabeam/seabeam.for
Description
  Program to convert Seabeam (EEZ) UTM bathymetric data grids to 

     Lat, Long, Depth (meters).
       
PROMPTS
  ' Enter a latitude limit:'

  ' Enter the other latitude limit:'
  ' Enter a longitude limit:'
  ' Enter the other longitude limit:'
    
INPUT
  For the user -- only the lat/long window limits.

  For the program -- data maintained in pmg$seabeam is accessed.
    
OUTPUT
  SEABEAM.DAT  --  file of lat/long/depth

  SEABEAM.LOG  --  information about the SEABEAM.DAT retrieval
  SEABEAM.NC   --  default NAVPLT contour control file for these data
    
RELATED_PROGRAMS
  SEABEAMLIST  --  generates a list of data set names and coverage areas

                     of files currently in pmg$seabeam
  DEM          --  extracts DEM elevation data
  DEMLIST      --  generates a list of data set names and coverage areas 
                     of files currently in pmg$dem
  DBA          --  if desired, can be used to access SEABEAM  and other 
                     databases
    
MAINTENANCE
  Put new SEABEAM data sets with characteristics consistant with existing 

  files (i.e.: named ????.DAT and ????.PRU) into PMG$SEABEAM
  They are then automatically known to "SEABEAM".
    
BACKGROUND
  SEABEAM data sets are disseminated by NOAA/NOS as Gridded EEZ 

  Bathymetric Data.  
       
  Data were collected as multibeam swath soundings for depths greater
  than 100 meters and up to 200 nautical miles from U.S. coastlines
  (EEZ limits).  Standard NOS hydrographic data supplemented the
  EEZ multibeam data.  Only some areas have coverage.
   
  The data sets are produced as 0.5 degree latitude X 1 degree 
  longitude areas south of Alaska.  Areas around Alaska are
  0.5 degree X 1.5 degrees.  Some exceptions exist.
   
  Original data are typically collected with tracklines run generally
  parallel to known contours.  The swath is perpendicular to the
  trackline of the platform.  At least 10% sidelap is maintained.
  Swath width is about 70% of the water depth for depths greater
  than 600 meters.  For shallow water, the swath width is up to
  250% of the water depth.
   
  Data are disseminated as both 5.25" and 3.5" floppies.
  The PMG DAPS group has been designated by NOAA and OEMG as the 
  USGS west coast archivers and distributors of these data for the USGS.
  DAPS maintains online on ISDMNL a complete set of the highest
  resolution of these data.  Access is via:    "SEABEAM"
   
  The data used as highest resolution are UTM grids (.DAT files) and
  their headers (.PRU files).  
  The grid dimensions vary and are specified in the .PRU file.  
  The spacial resolution is 250 X 250 meters.  
  Use caution when using these data for scales larger than 1:100,000.
   
  The data files consists of a regular array of depths in meters 
  relative to sea level.  The data are ordered from north to
  south in profiles ("scan lines") that are ordered from west to east
  (i.e.: first point is NW corner, last point is SE corner).  Data are
  maintained as UTM's but converted during retrieval to lat/long.
   
  A second, more generalized data set is available on the floppies, but
  is not maintained online.  It contains data in a lat/long grid with
  a spacing of 15 arc-seconds (0.00416666... degrees).
   
  Data for these grids are derived from much denser raw data refered 
  to as "full resolution data" or "raw soundings".  Typically, there
  are 5 to 10 million such soundings for each area.  The data has a
  horizontal accuracy of 50 meters and +/- 1% error in depth.
  The depths have been corrected for the velocity of sound in water.
  Full resolution data sets are not yet available, but are planned
  to be distributed through NGDC.
   
  Selected soundings numbering about 300,000 per map area were chosen
  by NOAA from the "full resolution data".  These 300,000 soundings
  were computer contoured and gridded to produce the 250-meter UTM
  grids.  This UTM grid is used to produce the 15-second grid.
  Gridded depths are rounded to the nearest meter.
   
  Within the grids:
    no depths are given for land areas and some near-land areas, and
    indeterminate depths are designated as -32767
  "SEABEAM" removes such data from the output "SEABEAM.DAT"
    
  For a more complete description see:
        README.DOC FILE
        Documentation for Dissemination of NOAA/NOS Gridded EEZ
          Bathymetric Data, January 1991
        (Clint Steele, x3170 has a copy)
    
PROGRAMMING_CONSIDERATIONS
  SEABEAM data and header files are in ASCII and can be edited.

   
  "SEABEAM" reads the header file and expects certain information
  in certain records.  If this scheme is changed, "SEABEAM" will
  have to be made "smarter".
   
  The .DAT files consist of one sounding per record.  Information
  about the grid dimensions and starting point is necessary to
  correctly interpret the .DAT file.
   
  "SEABEAM" computes the UTM X and Y values then converts them to
  lat/long using zone information, etc. from the header file.
   
  For data formats, see the following code.  For a description of them,
  see the above mentioned document.
    
LIMITATIONS
  Expects EEZ UTM format.

    
SUBROUTINES
  vescinit            (shared DRS external routine) 

  lib$find_file       (VAX/VMS Run-Time routine)    
  forerror            (shared DRS external routine) 
  stringlen           (shared DRS external routine) 
  percentage          (shared DRS external routine) 
  utmtogeo            (internal)                    
    
FUNCTIONS
  index               (FORTRAN intrinsic function)  

    
FILES_USED
  unit=*(write)

  unit=5(read)
  unit=6(write)
  unit=90(open,read,close)
  unit=91(open,read,close)
  unit=92(open,write,inqre,close)
  unit=93(open,write,inqre,close)
  unit=94(open,write,inqre,close)
    
AUTHOR
  Clint Steele      8/3/91


    
Reads
      read (HeadUnit, '(/,t29,a)')  PRUFileName
      read (HeadUnit, '(/,t34,a)')  MapName
      read (HeadUnit, '(t10,i7)')   Reference
      read (HeadUnit, '(t12,i5)')   YRows
      read (HeadUnit, '(t12,i5)')   XColumns
      read (HeadUnit, '(t11,i6)')   MinDepth
      read (HeadUnit, '(t11,i6)')   MaxDepth
      read (HeadUnit, '(t11,i6)')   UndefinedDepth
      read (HeadUnit, '(t9,f8.3)')  West
      read (HeadUnit, '(t9,f8.3)')  East
      read (HeadUnit, '(t9,f8.3)')  South
      read (HeadUnit, '(t9,f8.3)')  North
      read (HeadUnit, '(t5,f12.3)') Xmin
      read (HeadUnit, '(t5,f12.3)') Xmax
      read (HeadUnit, '(t5,f12.3)') Ymin
      read (HeadUnit, '(t5,f12.3)') Ymax
      read (HeadUnit, '(t8,f9.3)')  XResolution
      read (HeadUnit, '(t8,f9.3)')  YResolution
      read (HeadUnit, '(t14,i3)')   Zone
      read (HeadUnit, '(t13,i4)')   Datum
             read (InUnit, '(i)', iostat = ErrorFlag, end = 98) Depth
Writes
      write (LogUnit, 22) MapName(1:Length) 
                      write (OutUnit,3) X, Y, Depth, Lat, Lon
      write (LogUnit, '(a)') '*** ABNORMAL TERMINATION ***'
      write (LogUnit, 14) Zone, Datum
Opens
      open (unit = OutUnit,
     *      carriagecontrol = 'list',
     *      file = OutName,
     *      form = 'formatted',
     *      iostat = ErrorFlag,
     *      status = 'new')
      open (unit = LogUnit,
     *      carriagecontrol = 'list',
     *      file = LogName,
     *      form = 'formatted',
     *      iostat = ErrorFlag,
     *      status = 'new')
      open (unit = NCUnit,
     *      carriagecontrol = 'list',
     *      file = NCName,
     *      form = 'formatted',
     *      iostat = ErrorFlag,
     *      status = 'new')
      open (unit = HeadUnit,
     *      carriagecontrol = 'list',
     *      file = ControlName,
     *      form = 'formatted',
     *      iostat = ErrorFlag,
     *      status = 'old',
     *      shared,
     *      readonly)
      open (unit = InUnit,
     *      carriagecontrol = 'list',
     *      file = DataName,
     *      form = 'formatted',
     *      iostat = ErrorFlag,
     *      status = 'old',
     *      shared,
     *      readonly)
Calls
      call degrees (LimitNorth, LimitSouth, LimitWest, LimitEast)
          call lib$find_file (SearchName, 
     *                        FileName(NumberFound), Context,,,,0)
      call logstart (LogUnit, OutUnit, NCUnit,
     *               LimitNorth, LimitSouth, LimitWest, LimitEast)
      call stringlen (MapName, Length)
                  call utmtogeo (X, Y, Zone, Lat, Lon, 'N')
      call forerror (ErrorFlag)
          call logpart (LogUnit, OutputCount, 'depth', 
     *        North,         South,      West,      East,
     *        TotalNorth,    TotalSouth, TotalWest, TotalEast,
     *        MinDepth,      MaxDepth,
     *        TotalMinDepth, TotalMaxDepth,
     *        '250 X 250 meters',
     *        '50 meters',     
     *        '1 meter', 
     *        '+/- 1 percent')
      call makecontur (NCUnit, TotalOutputCount, 
     *                 'Gridded Select Seabeam', 
     *                 TotalMinDepth, TotalMaxDepth,
     *                 LimitNorth, LimitSouth, LimitWest, LimitEast)
      call logend (LogUnit, OutUnit, NCUnit,
     *             'depth', TotalOutputCount, 
     *             TotalMinDepth, TotalMaxDepth,
     *             TotalNorth, TotalSouth, TotalWest, TotalEast)
          call tminv (yutm , xutm, rlat, rlon, a)

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Page Last Modified: Mon Sep 16 03:38:52 PDT 2013  (chd)