Describe the Problem

This issue was raised via dtcenter/METplus#1530. MET version 10.1.0 was enhanced to read rotated lat/lon grids from CF-compliant NetCDF files in #1055. This comment illustrates that it appears to be successful in doing so. However that sample data was somewhat lacking since there is no obvious relationship between the data (lighting strikes) and the underlying map data. Testing using a more recent MetOffice sample file for a rotated lat/lon grid over the UK reveals a significant problem.

plot_data_plane prods_op_ukv_20220301_00_000.nc prods_op_ukv_20220301_00_000.ps 'name="surface_altitude"; level="(*,*)";'

There is a clear offset between the data (surface altitude in meters) and the map data.

This issue to find the source of this discrepancy and fix it. Recommend also retrieving examples of other rotated lat/lon grid from the MetOffice and testing to confirm that the data is aligned correctly relative to the map data.

Expected Behavior

Plotting the surface altitude data for this grid should align correctly with the map data of the UK.

Environment

Describe your runtime environment:
1. Machine: tested on MacOS but not machine-specific
2. Software version number(s): MET version 10.1.0. Fix in the main_v10.1 and develop branches.

To Reproduce

Describe the steps to reproduce the behavior:
1. Run the following plot_data_plane command:

plot_data_plane prods_op_ukv_20220301_00_000.nc prods_op_ukv_20220301_00_000.ps 'name="surface_altitude"; level="(*,*)";'

Note the discrepancy between the data and map outlines.

Relevant Deadlines

Fix ASAP in version 10.1.1.

Funding Source

MetOffice account key?

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Assignee

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