NAME
        DensityCalc

   DESCRIPTION
        This module creates 2-D and 3-D curvilinear lattices representing the
        density of seawater over a range of temperature and salinity values.
        The 3-D lattice is simply the 2-D lattice extruded over time size.  The
        minimum, maximum, and scaling values along with the appropriate
        coordinates could come from the TSCoordinate module, which
        coordinates between the Tracer module and DensityCalc.
        
        The density is calculated using the standard equation of state
        recommended by UNESCO.  References:
        
           Gill, A., Atmosphere-Ocean Dynamics: International Geophysical
              Series No. 30. Academic Press, London, 1982, pp 599-600.
           UNESCO, 10th report of the joint panel on oceanographic tables
              and standards. UNESCO Tech. Papers in Marine Sci. No. 36,
              Paris, 1981.

   WIDGETS

      Temperature Min -- Dial
         This is the minimum temperature value.  It could come from the
         "Temperature Min" output port of TSCoordinate.

      Temperature Max -- Dial
         This is the maximum temperature value.  It could come from the
         "Temperature Max" output port of TSCoordinate.

      Temperature Scale -- Dial
         This is the scaling factor by which to multiply the temperature values.
         It could come from the "Temperature Scale" output port of
         TSCoordinate.

      Temperature Size -- Slider
         This is the number of grid spaces to use along the temperature axis.

      Salinity Min -- Dial
         This is the minimum salinity value.  It could come from the "Salinity Min"
         output port of TSCoordinate.

      Salinity Max -- Dial
         This is the maximum salinity value.  It could come from the "Salinity Max"
         output port of TSCoordinate.

      Salinity Scale -- Dial
         This is the scaling factor by which to multiply the salinity values.  It
         could come from the "Salinity Scale" output port of TSCoordinate.

      Salinity Size -- Slider
         This is the number of grid spaces to use along the salinity axis.

      Time Min -- Dial
         This is the minimum time value.  It could come from the "Time Min"
         output port of TSCoordinate.

      Time Max -- Dial
         This is the maximum time value.  It could come from the "Time Max"
         output port of TSCoordinate.

      Time Scale -- Dial
         This is the scaling factor by which to multiply the time values.  It
         could come from the "Time Scale" output port of TSCoordinate.

      Time Size -- Slider
         This is the number of grid points to use along the time axis.  It is
         only meaningful for the 3-D density lattice.  A value of two is
         usually sufficient.

      Fixed Coordinate -- Option Menu
         This is the axis of the temperature/salinity plane that will be fixed.  It
         could come from the "Fixed Coordinate" output port of TSCoordinate.

      Fixed Value -- Dial
         This is the coordinate value at which to fix the temperature/salinity
         plane along the fixed axis.  It could come from the "Fixed Value" output
         port of TSCoordinate.

      Orientation -- Option Menu
         This is the orientation of the temperature/salinity plane.  It determines
         whether the plane is temperature/salinity or salinity/temperature.  It
         could come from the "Orientation" output port of TSCoordinate.

   OUTPUTS

      Density 2-D -- Lattice
         (2-D, 1-vector, float, curvilinear, 3-cD).
         This is a 2-D curvilinear lattice of density values with temperature,
         salinity, and time coordinates.  It could be sent to the Contour module.

      Denstiy 3-D -- Lattice
         (3-D, 1-vector, float, perimeter).
         This is a 3-D perimeter lattice of density values with temperature,
         salinity, and time coordinates.  It could be sent to the IsosurfaceLat
         module.

   KNOWN PROBLEMS
      There are no known bugs.

   SEE ALSO
      Contour, Contour2, ContourNaN, IsosurfaceLat, Tracer, TSCoordinate
      
      -
      
      Hans Vahlenkamp (Hans.Vahlenkamp@noaa.gov)
      Geophysical Fluid Dynamics Laboratory / NOAA
      Princeton University Forrestal Campus
      http://www.gfdl.noaa.gov