grdvolume

       grdvolume  -  Calculating  volume under a surface within a
       contour

SYNOPSIS

       grdvolume grdfile [ -Ccval or -Clow/high/delta ] [  -Lbase
       ]  [ -Rwest/east/south/north[r] ] [ -S[k] ] [ -T ] [ -V[l]
       ] [ -Zfact[/delta] ]

DESCRIPTION

       grdvolume reads a 2-D binary grd file and  calculates  the
       volume  contained between the surface and the plane speci­
       fied by the given contour (or zero if not given).   Alter­
       natively, specify a range of contours to be tried and grd­
       volume will determine the volume and area inside the  con­
       tour for all contour values. The contour that produced the
       maximum mean height (volume/area)  is  reported  as  well.
       This  feature  may  be used with grdfilter in designing an
       Optimal Robust Separator [Wessel, 1998].

       grdfile
              The name of the input 2-D binary grd file.

OPTIONS

       No space between the option flag and the associated  argu­
       ments.

       -C     find  area  and  volume  inside  the  cval contour.
              Alternatively, search using all contours  from  low
              to  high in steps of delta. [Default returns entire
              area and volume of grid].

       -L     Also add in the volume from the level of  the  con­
              tour down to base [Default base is contour].

       -S     Convert degrees to meters, append k for km [Default
              is Cartesian].

       -T     Use curvature minimum rather than maximum height to
              find  best  contour  value  (when contour search is
              selected with -C).

       -R     west, east, south, and north specify the Region  of
              interest. To specify boundaries in degrees and min­
              utes [and  seconds],  use  the  dd:mm[:ss]  format.
              Append  r if lower left and upper right map coordi­
              nates are given instead of wesn.

       -V     Selects verbose  mode,  which  will  send  progress
              reports   to   stderr  [Default  runs  "silently"].
              Append l to see all the results  for  each  contour
              level   tested   (when   contour  search  has  been
              selected).
              fact.  [Default is no scaling].  (Numbers in -C, -L
              refer to values after this scaling has occurred).

EXAMPLES

       To  determine  the  volume  in  km^3  under  the   surface
       hawaii_topo.grd (height in km), try

       grdvolume hawaii_topo.grd -Sk

       To  find  the volume between the surface peaks.grd and the
       contour z = 250, use

       grdvolume peaks.grd -Sk -C250

       To search for the contour, between 100 and 300 in steps of
       10, that maximizes the ratio of volume to surface area for
       the file peaks.grd, use

       grdvolume peaks.grd -Sk -C100/300/10 > results.d

       To see the areas and volumes for all the countours in  the
       previous example, try

       grdvolume peaks.grd -Sk -Vl -C100/300/10 > results.d

SEE ALSO

       gmt(l), grdfilter(l)

REFERENCES

       Wessel,  P.,  1998, An empirical method for optimal robust
       regional-residual separation of  geophysical  data,  Math.
       Geol., 30(4), 391-408.