Add documentation for Multivariate MODE to the MET User's Guide.

[JohnHalleyGotway]

Describe the Task

MET #1184 adds support for multi-variate MODE, but due to time and funding limitations, the corresponding documentation changes are not included with the code changes. This task is to update the MET User's Guide with information about multi-variate MODE.

Time Estimate

1 day (?)

Sub-Issues

Consider breaking the task down into sub-issues.
No sub-issues required.

Relevant Deadlines

Required by the met-10.0.0 release.

Funding Source

Define the source of funding and account keys here or state NONE.
2700042

Define the Metadata

Assignee

• Select engineer(s) or no engineer required: no engineer required
• Select scientist(s) or no scientist required: Lindsay

Labels

• Select component(s)
• Select priority
• Select requestor(s)

Projects and Milestone

• Review projects and select relevant Repository and Organization ones or add "alert:NEED PROJECT ASSIGNMENT" label
• Select milestone to next major version milestone or "Future Versions"

Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdatadb, METviewer, METexpress, METcalcpy, METplotpy
  No impacts.

Task 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.
• Submit a pull request to merge into develop.
  Pull request: feature <Issue Number> <Description>
• Define the pull request metadata, as permissions allow.
  Select: Reviewer(s), Project(s), Milestone, and Linked issues
• Iterate until the reviewer(s) accept and merge your changes.
• Delete your fork or branch.
• Close this issue.

[JohnHalleyGotway]

Please see this MET-Help ticket:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=98171

Looking in the MET User's Guide at the chapter about MODE:https://dtcenter.github.io/MET/latest/Users_Guide/mode.html

This description is not sufficient:

The field entries in the forecast and observation dictionaries specify the model and observation variables and level to be compared. See a more complete description of them in Section 3.5.1. In the above example, the forecast settings are copied into the observation dictionary using obs = fcst;.

All we're doing there is referring to the common config file options section about setting the "field" entry. I realize that we should modify that to point out that in MODE the "field" is defined as a single dictionary entry... and not as an array of fields.

However, one complication is that in MET version 10.0.0, "field" can either be set to a single entry or an array of entries. If it's an array of entries, then those multiple fields are combined into a single set of MODE objects rather than looping over the list and running MODE once for each.

I'm going to copy/paste this email as a comment on the GitHub issue for updating the multi-variate MODE documentation:#1592

Thanks for pointing out the confusion.