"Smooth Boundary velocities" in pyGplates

Sia · 10 September 2021 05:35

Hi all, I am trying to use pygplates for getting paleo-velocities at the surface, similar to the tutorial in here:

GPlates/pygplates-tutorials/blob/master/libs/velocity_utils.py

import pygplates
import numpy as np

def make_GPML_velocity_feature(Long,Lat):
# function to make a velocity mesh nodes at an arbitrary set of points defined in Lat
# Long and Lat are assumed to be 1d arrays. 

    # Add points to a multipoint geometry
    multi_point = pygplates.MultiPointOnSphere([(float(lat),float(lon)) for lat, lon in zip(Lat,Long)])

    # Create a feature containing the multipoint feature, and defined as MeshNode type
    meshnode_feature = pygplates.Feature(pygplates.FeatureType.create_from_qualified_string('gpml:MeshNode'))
    meshnode_feature.set_geometry(multi_point)
    meshnode_feature.set_name('Velocity Mesh Nodes from pygplates')

    output_feature_collection = pygplates.FeatureCollection(meshnode_feature)
    
    # NB: at this point, the feature could be written to a file using
    # output_feature_collection.write('myfilename.gpmlz')

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In Gplates (the gui), when exporting plate velocities using any of the four file formats (GMT, GPML, Sitcom, Terra) one has the option to have smooth velocities at the boundaries, with a “degree” parameters that one can set. Is there a possibility to do the same, i.e., have smoother velocities within some distance of the boundaries? I have looked at the documentation for pygplates and could not find anything there.

Regards,
Sia

john.cannon · 10 September 2021 08:29

Hi Sia,

That should be in the next pyGPlates release.

One of the main purposes of that release will be to handle velocities better (ie, easier to calculate them, including within deforming regions and on plate boundaries; and provide those export format options you mentioned).

Sia · 15 September 2021 05:06

Hi John,

This sounds awesome. More features for handling of velocities will be definitely useful when linking pygplates with other codes, specially convection codes. Looking forward to the release.

All the best,
Sia