Describe the New Feature

This new feature request was originally combined with #1954 but has been split off into this separate issue.

MET needs to be enhanced to supported gridded NetCDF files following the UGRID convention (Conventions = "UGRID"):
ugrid-conventions.github.io/ugrid-conventions

Recommend doing development using both LFRic and MPAS NetCDF files side-by-side. This will require a new vx_data2d_ugrid library to extract data from these NetCDF files. In addition, it'll require a new unstructured grid class in the vx_grid library.

The UGRID grid class will need to link to the source NetCDF file since it must be queried while working with it. One key piece of functionality will be instantiating a kdtree for that UGRID. Recommend leveraging an external C++ library rather than coding that up ourselves.

Some pieces of functionality we'll need to add are:

• Enhance Point-Stat to verify points natively on the UGRID.
• Consider parallelizing the loop for interpolating model data to point locations to make it as fast as possible.
• Support nearest neighbor as well as the min/max/uw_mean/dw_mean of the nearest N points.
• Enhance Grid-Stat and Series-Analysis to compare UGRID to UGRID on the same grid.

Future considerations include:

• Using lookup tables to make the interpolation to point locations more efficient rather than calling kdtrees.

Acceptance Testing

List input data types and sources.
Describe tests required for new functionality.

Time Estimate

Weeks

Sub-Issues

Consider breaking the new feature down into sub-issues.

• Add a checkbox for each sub-issue here.

Relevant Deadlines

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Funding Source

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2799991 Met Office METplus Support & 7705991 MPAS participation

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Assignee

• Select engineer(s) or no engineer required: @JohnHalleyGotway
• Select scientist(s) or no scientist required: @willmayfield

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Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdataio, METviewer, METexpress, METcalcpy, METplotpy
• May want separate issues for plotting UGRID data but I don't think these changes have any direct impacts on other repos.

New Feature Checklist

See the METplus Workflow for details.

• Complete the issue definition above, including the Time Estimate and Funding source.
• Fork this repository or create a branch of develop.
  Branch name: feature_<Issue Number>_<Description>
• Complete the development and test your changes.
• Add/update log messages for easier debugging.
• Add/update unit tests.
• Add/update documentation.
• Push local changes to GitHub.
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  Pull request: feature <Issue Number> <Description>
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  Select: Reviewer(s) and Linked issues
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• Iterate until the reviewer(s) accept and merge your changes.
• Delete your fork or branch.
• Close this issue.