Switch to 2DVar for snow DA

[CoryMartin-NOAA]

What new functionality do you need?

Move from LETKF-OI with a fake ensemble to 2DVar

What are the requirements for the new functionality?

Move from LETKF-OI with a fake ensemble to 2DVar

See NOAA-EMC/GDASApp#1324 for the companion issue

Acceptance Criteria

• Cycled DA works with snow 2DVar

Suggest a solution (optional)

No response

[CoryMartin-NOAA]

Work has been progressing in CoryMartin-NOAA:feature/snow-da-refactor. However there is currently an issue with assimilation of the IMS snow cover data that is being investigated. No timeline yet on when a PR will be opened.

[CoryMartin-NOAA]

IMS issue has been resolved (was a stupid YAML templating mistake with an extraneous mismatched quote) but there is an issue with the linear variable change in the GDAS 2DVar. Still investigating that problem, not sure if it is configuration, input files, or source code related

[CoryMartin-NOAA]

All issues have been resolved for the snow DA (I think). Will do a final test now that I've generated new NICAS files. Once I know the new files are working properly, I'll open an issue to have them staged, and once they're staged, will open the PR

[CoryMartin-NOAA]

a draft PR will be opened either tomorrow or Thursday, but a full PR will require NOAA-EMC/GDASApp#1410 to be merged in