ex01_ant_rf

This example removes the existing topography from the Cascadia ANT+RF shear-wave velocity model with -Or+t and then adds dry-land topography to that flattened model with -Oa+t using each of the three topobath construction methods. Wet columns remain outside the selected operation scope.

The shared Earth relief grid is a one-arc-minute crop of GMT’s @earth_relief_01m_g dataset over longitude/latitude = -130/-116/39/52. The script creates and caches this 1 MB regional grid if it is unavailable. All topobath operations use the smaller local file.

The ANT+RF model stores depth in kilometers, positive downward. The relief grid stores elevation in meters, positive upward, so +z-0.001+Zkm converts its values to the model convention before sampling. The output axes increase from the top (zmin) to the bottom (zmax):

-T0/10/0.1   flattened model from 0 to 10 km depth
-T-5/2/0.1   topographic models from 5 km elevation to 2 km depth

The deeper flattened model retains enough source material for columns shifted upward by the pull-up/push-down method; the figures display only the upper 2 km.

The model uses zero as its shallow water or air marker. -WVs/0+t0.01 therefore identifies old water columns and writes zero shear-wave velocity where new bathymetry creates water. -Dh -A0/0/1 uses high-resolution GSHHG ocean and land polygons as the inference prior. Columns outside the ANT+RF model coverage remain NaN.

The diagnostics figure contains the inferred elevation, inference classes, the original latitude = 47 N section, and the flattened section. Class 0 marks unresolved columns outside the model coverage, class 1 marks land, and class 2 would mark a seafloor inferred from water values.

The methods figure compares the flattened baseline with:

  • -Oa+t -Mp: pull-up/push-down construction

  • -Oa+t -Me: constant one-dimensional construction

  • -Oa+t -Ml -LVs/0.5: linear construction to 0.5 km/s at the land surface

The top row shows Vs at zero depth. The bottom row shows latitude = 47 N sections from 5 km elevation to 2 km depth. Dashed lines on the maps mark the section location, and solid lines on the sections mark the applied surface.

Run:

./ex01_ant_rf.sh

Intermediate NetCDF models are removed when the script exits. The script creates:

  • ex01_ant_rf_diagnostics.png and ex01_ant_rf_diagnostics.pdf

  • ex01_ant_rf_methods.png and ex01_ant_rf_methods.pdf

Figures

ex01_ant_rf ex01_ant_rf

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