Provided by: gmt-common_5.4.5+dfsg-2_all bug


       grdseamount  -  Compute  synthetic  seamount  (Gaussian  or  cone, circular or elliptical)


       grdseamount [ intable ]
        -Rregion [  -A[out/in] ] [  -Cc|d|g|p ] [  -D[unit] ] [   -E  ]  [   -F[flattening]  ]  [
       -Ggrdfile  ]  [   -L[cut]  ]  [   -Mlist  ]  [  -Nnorm ] [  -Qbmode/qmode ] [  -Sscale ] [
       -Tt0[u][/t1[u]/dt[u]|n][+l] ] [  -Zlevel ] [  -V[level] ] [ -bibinary ] [ -eregexp ] [ -fg
       ] [ -iflags ] [ -r ]

       Note: No space is allowed between the option flag and the associated arguments.


       grdseamount  will  compute  the combined shape of multiple synthetic seamounts given their
       individual shape parameters.  We read a list with seamount locations  and  sizes  and  can
       evaluate  either  Gaussian,  parabolic,  conical, or disc shapes, which may be circular or
       elliptical, and optionally truncated.  Various scaling options are available to modify the
       result, including an option to add in a background depth (more complicated backgrounds may
       be added via grdmath).  The input must contain lon, lat, radius, height for each seamount.
       For  elliptical  features (-E) we expect lon, lat, azimuth, semi-major, semi-minor, height
       instead. If flattening is specified (-F) with no value appended then a final  column  with
       flattening  is  expected  (cannot  be  used  for  plateaus).   For  temporal  evolution of
       topography the -T option may be used, in which case the data  file  must  have  two  final
       columns  with  the  start  and  stop  time of seamount construction.  In this case you may
       choose to write out a cumulative shape or just the increments produced by each  time  step
       (see -Q).


              x_inc  [and  optionally  y_inc]  is  the  grid spacing. Optionally, append a suffix
              modifier. Geographical (degrees) coordinates: Append m to indicate arc minutes or s
              to  indicate  arc  seconds.  If  one  of  the  units e, f, k, M, n or u is appended
              instead, the increment is assumed to be given in meter, foot,  km,  Mile,  nautical
              mile  or  US  survey  foot,  respectively,  and will be converted to the equivalent
              degrees longitude at the middle latitude of the region (the conversion  depends  on
              PROJ_ELLIPSOID).  If  y_inc  is given but set to 0 it will be reset equal to x_inc;
              otherwise it will be converted to degrees  latitude.  All  coordinates:  If  +e  is
              appended  then the corresponding max x (east) or y (north) may be slightly adjusted
              to fit exactly the given increment  [by  default  the  increment  may  be  adjusted
              slightly  to fit the given domain]. Finally, instead of giving an increment you may
              specify the number of nodes  desired  by  appending  +n  to  the  supplied  integer
              argument;  the  increment  is  then  recalculated  from the number of nodes and the
              domain. The resulting increment value  depends  on  whether  you  have  selected  a
              gridline-registered  or  pixel-registered  grid;  see App-file-formats for details.
              Note: if -Rgrdfile is used then the grid spacing has already been initialized;  use
              -I to override the values.

       -Rxmin/xmax/ymin/ymax[+r][+uunit] (more ...)
              Specify the region of interest.


              Build  a  mask grid, append outside/inside values [1/NaN].  Here, height is ignored
              and -L, -N and -Z are disallowed.

       -C     Select shape function: choose  among  c  (cone),  d  (disc),  g  (Gaussian)  and  p
              (parabolic) shape [Default is Gaussian].

       -Dunit Append  the unit used for horizontal distances in the input file (see UNITS).  Does
              not apply for geographic data (-fg) which we convert to km.

       -E     Elliptical data format. We expect the input records to contain lon,  lat,  azimuth,
              major,  minor,  height  (with   the  latter  in  m) for each seamount.  [Default is
              Circular data format, expecting lon, lat, radius, height].

              Seamounts are to be truncated to guyots.  Append flattening, otherwise we expect to
              find it in last input column [no truncation].  Ignored if used with -Cd.

              Specify  the  name of the output grid file; see GRID FILE FORMATS below).  If -T is
              set then grdfile must be a filename template that contains a floating point  format
              (C syntax).  If the filename template also contains either %s (for unit name) or %c
              (for unit letter) then we use the corresponding time (in units specified in -T)  to
              generate the individual file names, otherwise we use time in years with no unit.

              List  area,  volume,  and  mean  height  for  each  seamount;  No  grid is created.
              Optionally, append the noise-floor cutoff level below  which  we  ignore  area  and
              volume [0].

       -Mlist Write the names of all grids that were created to the text file list.  Requires -T.

       -Nnorm Normalize grid so maximum grid height equals norm.

              Only  to  be used in conjunction with -T.  Append two different modes settings: The
              bmode determines how we construct the surface.  Specify  c  for  cumulative  volume
              through  time,  or  i  for incremental volume added for each time slice.  The qmode
              determines the volume flux curve.  Give g for a Gaussian volume flux history  or  l
              for a linear volume flux history between the start and stop times of each feature.

              Sets optional scale factor for radii [1].

              Specify  t0,  t1,  and time increment (dt) for sequence of calculations [Default is
              one step, with no time dependency].  For a single specific time,  just  give  start
              time t0. The unit is years; append k for kyr and M for Myr.  For a logarithmic time
              scale, append +l and specify n steps instead of dt.   Alternatively,  give  a  file
              with  the  desired times in the first column (these times may have individual units
              appended, otherwise we assume year).  Note that the grid for  t0  (if  a  range  is
              given) is not written as it is zero and marks the start of the building history.

              Set the background depth [0].

       -bi[ncols][t] (more ...)
              Select native binary input. [Default is 4 input columns].

       -e[~]"pattern" | -e[~]/regexp/[i] (more ...)
              Only accept data records that match the given pattern.

       -fg    Geographic  grids (dimensions of longitude, latitude) will be converted to km via a
              "Flat Earth" approximation using the current ellipsoid parameters.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more ...)
              Skip or produce header record(s). Not used with binary data.

       -icols[+l][+sscale][+ooffset][,...] (more ...)
              Select input columns and transformations (0 is first column).

       -V[level] (more ...)
              Select verbosity level [c].

       -r (more ...)
              Set pixel node registration [gridline].

       -:[i|o] (more ...)
              Swap 1st and 2nd column on input and/or output.

       -^ or just -
              Print a short message about the syntax of the command, then exits (NOTE: on Windows
              just use -).

       -+ or just +
              Print  an  extensive  usage  (help)  message,  including  the  explanation  of  any
              module-specific option (but not the GMT common options), then exits.

       -? or no arguments
              Print a complete usage (help) message, including the explanation  of  all  options,
              then exits.


       For  map  distance  unit,  append  unit  d for arc degree, m for arc minute, and s for arc
       second, or e for meter [Default], f for foot, k for km, M for statute mile, n for nautical
       mile,  and  u  for  US survey foot. By default we compute such distances using a spherical
       approximation with great circles. Prepend - to a distance (or the unit is no  distance  is
       given)  to  perform  "Flat Earth" calculations (quicker but less accurate) or prepend + to
       perform exact geodesic calculations (slower but more accurate).


       To compute the incremental loads from two elliptical, truncated Gaussian  seamounts  being
       constructed  from  3  Ma  to 2 Ma and 2.8 M to 1.9 Ma using a linear volumetric production
       rate, and output an incremental grid every 0.1 Myr from 3 Ma to 1.9 Ma, we can try:

          cat << EOF > t.txt
          #lon lat azimuth, semi-major, semi-minor, height tstart tend
          0   0       -20     120     60      5000    3.0M    2M
          50  80      -40     110     50      4000    2.8M    21.9M
          gmt grdseamount -Rk-1024/1022/-1122/924 -I2000 t.txt -T3M/1.9M/0.1M -Qi/l -Dk -E -F0.2 -Cg -Ml.lis


       gmt.conf, gmt, grdmath, gravfft, gmtflexure


       2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe