grdpmodeler — GMT 5.1.1 documentation

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# grdpmodeler

grdpmodeler - Evaluate a plate model on a geographic grid

## Synopsis

grdpmodeler agegrdfile -Erot_file -Goutgrdfile -Sa|d|r|w|x|y|X|Y [ -Fpolygonfile ] [ -Tage ] [ -V[level] ] [ -b[i|o][ncol][type][w][+L|+B] ] [ -h[i|o][n][+c][+d][+rremark][+rtitle] ] [ -icols[l][sscale][ooffset][,...] ] [ -:[i|o] ]

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

## Description

grdpmodeler reads a geographical age grid and a plate motion model and evaluates one of several model predictions. Optionally, the user may supply a clipping polygon in multiple-segment format; then, only the part of the grid inside the polygon is used to determine the model prediction; the remainder of the grid is set to NaN.

## Required Arguments

ingrdfile
  Name of a grid file in geographical (lon, lat) coordinates with ages in Myr.
-Erotfile

  Give file with rotation parameters. This file must contain one record for each rotation; each record must be of the following format:

  lon lat tstart [tstop] angle [ khat a b c d e f g df ]

  where tstart and tstop are in Myr and lon lat angle are in degrees. tstart and tstop are the ages of the old and young ends of a stage. If tstop is not present in the record then a total reconstruction rotation is expected and tstop is implicitly set to 0 and should not be specified for any of the records in the file. If a covariance matrix C for the rotation is available it must be specified in a format using the nine optional terms listed in brackets. Here, C = (g/khat)*[ a b d; b c e; d e f ] which shows C made up of three row vectors. If the degrees of freedom (df) in fitting the rotation is 0 or not given it is set to 10000. Blank lines and records whose first column contains # will be ignored. You may prepend a leading + to the filename to indicate you wish to invert the rotations. Alternatively, give the filename composed of two plate IDs separated by a hyphen (e.g., PAC-MBL) and we will instead extract that rotation from the GPlates rotation database. We return an error if the rotation cannot be found.

-Goutgrdfile
  Name of output grid. This is the grid with the model predictions given the specified rotations.
-Sa|d|r|w|x|y|X|Y
  Type of model prediction. Choose from a for plate motion azimuth, d for distance between current locations and their origin at the ridge (in km), r for plate motion rate (in mm/yr), w for plate rotation rate (degree/Myr), x change in longitude relative to location of crust formation, y change in latitude relative to location of crust formation, X longitude of crust formation, and Y latitude of crust formation.

## Optional Arguments

-Fpolygonfile
  Specify a multisegment closed polygon file that describes the inside area of the grid where the model should be evaluated; the outside will be set to NaN [Default evaluates model on the entire grid].
-Tage
  Use a fixed age for model evaluation (i.e., override the ages in the age grid). This lets you evaluate the model at a snapshot in time.

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

-bi[ncols][type] (more ...)
  Select binary input. [Default is 2 input columns].

-h[i|o][n][+c][+d][+rremark][+rtitle] (more ...)
  Skip or produce header record(s).

-icols[l][sscale][ooffset][,...] (more ...)
  Select input columns.

-^
  Print a short message about the syntax of the command, then exits (NOTE: on Windows use just -).
+
  Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exits.
-?
  Print a complete usage (help) message, including the explanation of options, then exits.
--version
  Print GMT version and exit.
--show-datadir
  Print full path to GMT share directory and exit.

## Examples

We will use a grid with Pacific crust ages (pac_age.nc), a plate motion model (Pac_APM.d), and a polygon that contains the outline of the present Pacific plate (pac_clip_path.d). To evaluate the plate motion azimuths at the present time for the Pacific, try

>     gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
>                     -Gpac_dir_0.nc -Sa -T0

To determine the changes in latitude since crust formation for the entire Pacific, try

>     gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
>                     -Gpac_dlat.nc -Sy

To determine the plate motion rates in effect when the Pacific crust was formed, try

>     gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
>                     -Gpac_vel.nc -Sr

To determine how far the crust has moved since formation, try

>     gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
>                     -Gpac_dist.nc -Sd

## See Also

backtracker, grdrotater, grdspotter, hotspotter, originator, rotconverter

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