(33) Stacking automatically generated cross-profiles — GMT 5.1.1 documentation

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# (33) Stacking automatically generated cross-profiles

The script produces the plot in Figure. Here we demonstrate how grdtrack can be used to automatically create a suite of crossing profiles of uniform spacing and length and then sample one or more grids along these profiles; we also use the median stacking option to create a stacked profile, showed above the map, with the gray area representing the variations about the stacked median profile.

    #!/bin/bash
    #               GMT EXAMPLE 33
    #               $Id $
    #
    # Purpose:      Illustrate grdtrack's new cross-track and stacking options
    # GMT progs:    makecpt, gmtconvert, grdimage, grdgradient, grdtrack, pstext, psxy
    # GMT progs:    pscoast, pstext
    # Unix progs:   cat, rm
    #
    ps=example_33.ps

    # Extract a subset of ETOPO1m for the East Pacific Rise
    # gmt grdcut etopo1m_grd.nc -R118W/107W/49S/42S -Gspac.nc
    gmt makecpt -Crainbow -T-5000/-2000/500 -Z > z.cpt
    gmt grdgradient spac.nc -A15 -Ne0.75 -Gspac_int.nc
    gmt grdimage spac.nc -Ispac_int.nc -Cz.cpt -JM6i -P -Baf -K -Xc --FORMAT_GEO_MAP=dddF > $ps
    # Select two points along the ridge
    cat << EOF > ridge.txt
    -111.6	-43.0
    -113.3	-47.5
    EOF
    # Plot ridge segment and end points
    gmt psxy -Rspac.nc -J -O -K -W2p,blue ridge.txt >> $ps
    gmt psxy -R -J -O -K -Sc0.1i -Gblue ridge.txt >> $ps
    # Generate cross-profiles 400 km long, spaced 10 km, samped every 2km
    # and stack these using the median, write stacked profile
    gmt grdtrack ridge.txt -Gspac.nc -C400k/2k/10k -Sm+sstack.txt > table.txt
    gmt psxy -R -J -O -K -W0.5p table.txt >> $ps
    # Show upper/lower values encountered as an envelope
    gmt gmtconvert stack.txt -o0,5 > env.txt
    gmt gmtconvert stack.txt -o0,6 -I -T >> env.txt
    gmt psxy -R-200/200/-3500/-2000 -Bxafg1000+l"Distance from ridge (km)" -Byaf+l"Depth (m)" -BWSne \
    	-JX6i/3i -O -K -Glightgray env.txt -Y6.5i >> $ps
    gmt psxy -R -J -O -K -W3p stack.txt >> $ps
    echo "0 -2000 MEDIAN STACKED PROFILE" | gmt pstext -R -J -O -K -Gwhite -F+jTC+f14p -Dj0.1i >> $ps
    gmt psxy -R -J -O -T >> $ps
    # cleanup
    rm -f gmt.conf z.cpt spac_int.nc ridge.txt table.txt env.txt stack.txt

Stacking automatically generated cross-profiles.

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