Lighting in vicinity cell_method alignment for master

[bayliffe]

In the global data lightning diagnostic that is created within improver we manually create the cell method.
The method is stated as "Sum" with a capital s, which doesn't match the lower case "sum" in the UK model diagnostics with which is blended. When the cubes are combined before merging the data the cell_methods are checked in the MergeCubes plugin and they all get thrown away.

Additionally, following the generalisation of the vicinity method to allow for mins, means etc. as well as maxes, an additional cell method is added to specify the form of the vicinity that has been applied. When vicinities are applied via the threshold step these cell methods are not added. ENGLUK lightning in vicinity data uses the vicinity CLI and thus gets this extra "area" cell method that is not present on the data from UKVX and ENUKX. This is a further source of difference between the two.

This PR:

• sets the manually created cell_method to use lowercase "sum" to match the other diagnostics.
• provides an option to omit the cell_method when applying the vicinity CLI. This is not desirable in general, but allows us to align the metadata for lightning without having to modify the cell methods of all other vicinity diagnostics by modifying the threshold applied vicinities.

Associated suite PR: https://github.com/MetOffice/improver_suite/pull/2623
Associated acceptance test data: metoppv/improver_test_data#121

Testing:

• Ran tests and they passed OK
• Added new tests for the new feature(s)

Testing in the suites

• https://cylchub/services/cylc-review/cycles/benjamin.ayliffe/?suite=lightning_master%2Fimukvx
• https://cylchub/services/cylc-review/cycles/benjamin.ayliffe/?suite=lightning_master%2Fimenukx
• https://cylchub/services/cylc-review/cycles/benjamin.ayliffe/?suite=lightning_master%2Fimenukx
• https://cylchub/services/cylc-review/cycles/benjamin.ayliffe/?suite=lightning_master%2Fimmix

Metadata in model suites

The tables below demonstrate that the metadata is now consistent across the various model suites by the time we get to the latestlevel2 feeding steps (blendcycles). The 3-hour diagnostic differs at the combine step as it feeds again from the standardise step before then having the cell method modified to the expected once again.

lightning1h (T+12 as an example)

Model	Step	Cell method
imukvx	fetchlevel1	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=()),)
imukvx	standardise	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=()),)
imenukx	fetchlevel1	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=()),)
imenukx	standardise	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=()),)

lightningvic1h (T+12 as an example)

Model	Step	Cell method
imukvx	threshold	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imukvx	nbhood	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imukvx	recfilter	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imukvx	blendcycles	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	threshold	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	nbhood	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	recfilter	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	blendcycles	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	lightning_filter	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	regrid	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	vicinity	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	nbhood	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	realization_collapse	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	blendcycles	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	recfilter	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)

lightningvic3h (T+12 as an example)

Model	Step	Cell method
imukvx	combine	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=()),)
imukvx	threshold	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imukvx	nbhood	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imukvx	recfilter	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imukvx	blendcycles	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	combine	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=()),)
imenukx	threshold	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	nbhood	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	recfilter	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imenukx	blendcycles	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	combine	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	regrid	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	vicinity	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	nbhood	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	realization_collapse	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	blendcycles	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
imengluk	recfilter	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)

Metadata in blending suite

lightningvic1h (T+12 as an example)

Model	Step	Cell method
immix	latestblend	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
immix	spot_extract	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)

lightningvic3h (T+12 as an example)

Model	Step	Cell method
immix	latestblend	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
immix	spot_extract	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)

lightningvic3h (T+122 as an example beyond the UK model contributions)

Model	Step	Cell method
immix	latestblend	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)
immix	spot_extract	(CellMethod(method='sum', coord_names=('time',), intervals=(), comments=('of number_of_lightning_flashes_per_unit_area',)),)

[gavinevans]

Thanks @bayliffe 👍

This looks fine. Acceptance tests pass once this PR is merged with #2297, and these two improver_test_data PRs are merged together: metoppv/improver_test_data#121, metoppv/improver_test_data#122.