correction to get time interpolation correct
- [ ] closes #21351
- [ ] One test does not pass and I don't know why

Hello @oricou! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:





There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2021-02-19 12:03:39 UTC > you need to either add a test or change current ones to show what you are changing.

Done but the "Missing-data" is still here... @oricou open source software is contributed by the community

the maintainers are donating time to review and comment and once the code meets all criteria it be merged 


 Thanks @oricou for taking the time to address this issue with the PR, but since this PR has gotten stale I'm going to close for now. If anyone else is interested in taking this up, happy to reopen. 