Add updates to MPR writer and fix bugs for stratosphere

[CPKalb]

Describe the New Feature

Updates to the write_mpr file needed for the stratosphere use case. This issue also includes fixing a bug in the zonal/meridional mean code

Acceptance Testing

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

Time Estimate

A few hours

Sub-Issues

Consider breaking the new feature down into sub-issues.

• Updates to write_mpr.py
• Bug fix for zonal and meridional mean code

Relevant Deadlines

List relevant project deadlines here or state NONE.

Funding Source

Contact Tara for account key

Define the Metadata

Assignee

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

Labels

• Review default alert labels
• Select component(s)
• Select priority
• Select requestor(s)

Milestone and Projects

• Select Milestone as a METcalcpy-X.Y.Z version, Consider for Next Release, or Backlog of Development Ideas
• For a METcalcpy-X.Y.Z version, select the METcalcpy-X.Y.Z Development project

Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdataio, METviewer, METexpress, METcalcpy, METplotpy

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.
• Add any new Python packages to the METplus Components Python Requirements table.
• 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) and Development issue
  Select: Milestone as the next official version
  Select: METcalcpy-X.Y.Z Development project for development toward the next official release
• Iterate until the reviewer(s) accept and merge your changes.
• Delete your fork or branch.
• Close this issue.