grdvolume - Calculating volume under a surface within a contour
grdvolume grdfile [ -Ccval or -Clow/high/delta ] [ -Lbase ] [
-Rwest/east/south/north[r] ] [ -S[k] ] [ -T ] [ -V[l] ] [
grdvolume reads a 2-D binary grd file and calculates the volume con-
tained between the surface and the plane specified by the given contour
(or zero if not given) and reports the area, volume, and maximum mean
height (volume/area). Alternatively, specify a range of contours to be
tried and grdvolume will determine the volume and area inside the con-
tour for all contour values. The contour that produced the maximum mean
height is reported as well. This feature may be used with grdfilter in
designing an Optimal Robust Separator [Wessel, 1998].
The name of the input 2-D binary grd file.
No space between the option flag and the associated arguments.
-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]. The area is
measured in the plane of the countour.
-L Also add in the volume from the level of the contour down to
base [Default base is contour].
-S Convert degrees to meters, append k for km [Default is Carte-
-T Use curvature minimum rather than maximum height to find best
contour value (when contour search is selected with -C).
-R xmin, xmax, ymin, and ymax specify the Region of interest. For
geographic regions, these limits correspond to west, east,
south, and north and you may specify them in decimal degrees or
in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left
and upper right map coordinates are given instead of wesn. The
two shorthands -Rg -Rd stand for global domain (0/360 or
-180/+180 in longitude respectively, with -90/+90 in latitude).
For calendar time coordinates you may either give relative time
(relative to the selected TIME_EPOCH and in the selected
TIME_UNIT; append t to -JX|x), or absolute time of the form
[date]T[clock] (append T to -JX|x). At least one of date and
clock must be present; the T is always required. The date string
must be of the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or
yyyy[-Www[-d]] (ISO week calendar), while the clock string must
be of the form hh:mm:ss[.xxx]. The use of delimiters and their
type and positions must be as indicated (however, input/output
and plotting formats are flexible).
-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
-Z Optionally subtract shift before scaling data by fact. [Default
is no scaling]. (Numbers in -C, -L refer to values after this
scaling has occurred).
To determine the volume in km^3 under the surface hawaii_topo.grd
(height in km), use
grdvolume hawaii_topo.grd -Sk
To find the volume between the surface peaks.grd and the contour z =
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,
grdvolume peaks.grd -Sk -C100/300/10 > results.d
To see the areas and volumes for all the contours in the previous exam-
grdvolume peaks.grd -Sk -Vl -C100/300/10 > results.d
Wessel, P., 1998, An empirical method for optimal robust regional-
residual separation of geophysical data, Math. Geol., 30(4), 391-408.
GMT4.0 1 Oct 2004 GRDVOLUME(l)
Man(1) output converted with