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backtracker
Langue: en
Version: 369039 (fedora - 01/12/10)
Section: 1 (Commandes utilisateur)
NAME
backtracker - Reconstruct points, flowlines and hotspot tracksSYNOPSIS
backtracker [infile(s)] -Erotations.txt | -elon/lat/angle [ -A[young/old] ] [ -C ] [ -Df|b ] [ -H[i][nrec] ] [ -Lf|bstep ] [ -Nupper_age ] [ -Qfixed_age ] [ -Sfilestem ] [ -Tzero_age ] [ -V ] [ -W[a|t] ] [ -:[i|o] ] [ -b[i|o][s|S|d|D[ncol]|c[var1/...]] ] [ -m[i|o][flag] ]DESCRIPTION
backtracker reads (longitude, latitude, age) positions from infiles [or standard input] and computes rotated (x,y,t) coordinates using the specified rotation parameters. It can either calculate final positions [Default] or create a sampled track (flowline or hotspot track) between the initial and final positions. The former mode allows additional data fields after the first 3 columns which must have (longitude,latitude,age). See option -: on how to read (latitude,longitude,age) files.No space between the option flag and the associated arguments. Use upper case for the
option flags and lower case for modifiers.
- infile(s)
- Data file(s) to be projected. If not given, standard input is read.
- -E
- 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 -C is set then a total reconstruction rotation is expected and tstop is implicitly set to 0 and should not be specified 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.
- -e
- Alternatively, specify the longitude, latitude, and opening angle (all in degrees and separated by /) for a single total reconstruction rotation that should be applied to all input points.
OPTIONS
- -A
- Used in conjunction with -Lb|f to limit the track output to those sections whose predicted ages lie between the specified young and old limits. If -LB|F is used instead then the limits apply to the stage ids (id 1 is the youngest stage). If no limits are specified then individual limits for each record are expected in columns 4 and 5 of the input file.
- -C
- Expect Total Reconstruction Rotations rather than Forward Stage Rotations [Default]. File format is similar to the stage pole format except that the tstart column is not present (assumed to be 0 Ma). Requires -E.
- -D
- Set the direction to go: -Df will go backward in time (from younger to older positions), while -Db will go forward in time (from older to younger positions) [Default]. Note: For -Db you are specifying the age at the given location, whereas for -Df you are not; instead you specify the age at the reconstructed point.
- -H
- Input file(s) has header record(s). If used, the default number of header records is N_HEADER_RECS. Use -Hi if only input data should have header records [Default will write out header records if the input data have them]. Blank lines and lines starting with # are always skipped.
- -L
- Specify a sampled path between initial and final position: -Lf will draw particle flowlines, while -Lb will draw backtrack (hotspot track) paths. Append sampling interval in km. If step < 0 then only the rotation times will be returned. When -LF or -LB is used, the third output column will contain the stage id (1 is youngest) [Default is along-track predicted ages]. You can control the direction of the paths by using -D.
- -N
- Set the maximum age to extend the oldest stage rotation back in time [Default is no extension].
- -Q
- Assign a fixed age to all positions. Only lon, lat input is expected [Default expects longitude, latitude, age]. Useful when the input are points defining isochrons.
- -S
- When -L is set, the tracks are normally written to stdout as a multisegment file. Specify a filestem to have each track written to filestem.#, where # is the track number. The track number is also copied to the 4th output column.
- -T
- Set the current time [Default is 0 Ma].
- -V
- Selects verbose mode, which will send progress reports to stderr [Default runs "silently"].
- -W
- Rotates the given input (lon,lat,t) and calculates the confidence ellipse for the projected point. The input point must have a time coordinate that exactly matches a particular finite rotation time, otherwise the point will be skipped. Append t or a to output time or angle, respectively, after the projected lon, lat. After these 2-3 items, we write azimuth, major, minor (in km) for the 95% confidence ellipse. See -D for the direction of rotation.
- -:
- Toggles between (longitude,latitude) and (latitude,longitude) input and/or output. [Default is (longitude,latitude)]. Append i to select input only or o to select output only. [Default affects both].
- -bi
- Selects binary input. Append s for single precision [Default is d (double)]. Uppercase S or D will force byte-swapping. Optionally, append ncol, the number of columns in your binary input file if it exceeds the columns needed by the program. Or append c if the input file is netCDF. Optionally, append var1/var2/... to specify the variables to be read. [Default is 3 input columns].
- -bo
- Selects binary output. Append s for single precision [Default is d (double)]. Uppercase S or D will force byte-swapping. Optionally, append ncol, the number of desired columns in your binary output file. [Default depends on settings].
- -m
- Multiple segment file(s). Segments are separated by a special record. For ASCII files the first character must be flag [Default is '>']. For binary files all fields must be NaN and -b must set the number of output columns explicitly. By default the -m setting applies to both input and output. Use -mi and -mo to give separate settings to input and output.
EXAMPLES
To backtrack the (x,y,t) points in the file seamounts.d to their origin (presumably the hotspot), using the DC85.d Euler poles, runbacktracker seamounts.d -Db -EDC85.d > newpos.d
To project flowlines forward from the (x,y,t) points stored in several 3-column, binary, double precision files, run
backtracker points.* -Df -EDC85.d -Lf25 -bo -bi3 > lines.b
This file can then be plotted with psxy -M.
SEE ALSO
GMT(1), project(1), mapproject(1), hotspotter(1), originator(1)REFERENCES
Wessel, P., 1999, "Hotspotting" tools released, EOS Trans. AGU, 80 (29), p. 319.Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre