In Chapter 5.6, grid_mapping can also be used for converting spatial bounds

[TomLav]

Title

In Chapter 5.6, grid_mapping can also be used for converting spatial bounds

Moderator

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Moderator Status Review [last updated: YYYY-MM-DD]

Brief comment on current status, update periodically

Requirement Summary

Since it isn't mandatory to provide 2D lat and lon auxiliary coordinate variables when the CRS and non-lat-lon 1D coordinate variables are provided, the same should apply to lat/lon bounds, because an application should be able to compute the bounds directly from the 1D bounds just like it can compute the lat/lon coordinates from the 1D coordinates. It's impossible anyway to provide lat/lon bounds if there are no lat/lon coordinate variables to attach them to.

Technical Proposal Summary

Insert a statement in Sec 5.6 "Horizontal Coordinate Reference Systems, Grid Mappings, and Projections" that the grid mapping information can be used to convert bounds as well as coordinates. At the moment it says nothing about bounds.

Benefits

This change will clarify that datasets provided in non lat/lon coordinate system, with a valid CRS, do not need to provide the full lat/lon bounds, only the bounds of the 1D coordinate variables, to express that the data variables are representative of cells (and not points). This might encourage data providers to provide said bounds (as it reduces file storage overhead).

Status Quo

This aspect (among others) was discussed here.

Associated pull request

#589

Detailed Proposal

A short paragraph about bounds is added to section 5.6, Horizontal Coordinate Reference Systems, ...

[JonathanGregory]

Thank you, Thomas. I support this change being made. I have made a couple of editorial comments in the PR. One further comment, on the words: I would suggest "the horizontal coordinates of the grid", instead of "easting and northings", for generality.

[TomLav]

Thank you for the editorial comments. I will also implement your suggestion "easting and northing" -> "the horizontal coordinates of the grid" as it is more general. I used easting and northing because this is what is used at the top of the section.

[JonathanGregory]

@TomLav. Since this is an enhancement, for which you have drafted the text as well as raising the need for it, please could you add yourself as an additional author of the convention in the PR. Also, the issue needs an entry in history.adoc. There should be heading for the new draft version in the Revision History. I've just created a PR to do this.

[TomLav]

Done. Exciting to be the first edit towards v1.13 :-)
I suppose there is no need to update the conformance document, so I put N/A for now.