.. index:: ! grdpmodeler *********** grdpmodeler *********** .. only:: not man grdpmodeler - Evaluate a plate motion model on a geographic grid Synopsis -------- .. include:: ../../common_SYN_OPTs.rst_ **grdpmodeler** *agegrdfile* |-E|\ *rot_file* **-S**\ *flags* [ |-F|\ *polygonfile* ] [ |-G|\ *outgrdfile* ] [ |-T|\ *age* ] [ |SYN_OPT-V| ] [ |SYN_OPT-b| ] [ |SYN_OPT-d| ] [ |SYN_OPT-h| ] [ |SYN_OPT-:| ] |No-spaces| 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. .. _-E: **-E**\ *rotfile* 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. .. _-S: **-S**\ *flags* Type of model prediction(s). Append one or more items: choose from **a** for plate motion azimuth, **d** for great-circle distance between current location and its origin at the ridge (in km), **s** for plate motion model stage ID (1 is youngest), **v** for plate motion rate (in mm/yr), **w** for plate rotation rate (degree/Myr), **x** for change in longitude relative to location of crust formation, **y** for change in latitude relative to location of crust formation, **X** for longitude of crust formation, and **Y** for latitude of crust formation. If no arguments are given we default to all [**adsvwxyXY**]. Optional Arguments ------------------ .. _-F: **-F**\ *polygonfile* 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]. .. _-G: **-G**\ *outgrdfile* Name of output grid. This is the grid with the model predictions given the specified rotations. Note: If you specified more than one model prediction in **-S** then the filename *must* be a template that contains the format %s; this will be replaced with the corresponding tags az, dist, stage, vel, omega, dlon, dlat, lon, lat. If the **-G** option is not used then we create no grids and instead write *lon, lat, age, predictions* records to standard output. .. _-T: **-T**\ *age* 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: .. |Add_-V| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_-V.rst_ .. |Add_-bi| replace:: [Default is 2 input columns]. .. include:: ../../explain_-bi.rst_ .. |Add_-d| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_-d.rst_ .. |Add_-h| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_-h.rst_ .. include:: ../../explain_help.rst_ .. include:: explain_geodetic.rst_ 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 velocities 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 -Sv 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 To save the coordinates of the crust's formation to separate grids, try :: gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \ -Gpac_origin_%s.nc -SXY To repeat the same exercise but save output *lon,lat,age,xorigin,yorigin* to a table, use :: gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d -SXY > origin.txt Notes ----- GMT distributes the EarthByte rotation model Global_EarthByte_230-0Ma_GK07_AREPS.rot. To use an alternate rotation file, create an environmental parameters named **GPLATES_ROTATIONS** that points to an alternate rotation file. See Also -------- :doc:`backtracker`, :doc:`gmtpmodeler`, :doc:`grdrotater`, :doc:`grdspotter`, :doc:`hotspotter`, :doc:`originator`, :doc:`rotconverter`