Fix file changes for iasi-ng_metop-sg-a1

[wx20jjung]

iasi-ng_metop-sg-a1 will need the a channel subset added to the global_satinfo.txt file, scan information added to the global_scaninfo.txt file and a cloud and aerosol detection software (CADS) file added to the GSI fix directory.

[RussTreadon-NOAA]

@wx20jjung , can we open a PR for the updated fix files?

[wx20jjung]

@RussTreadon-NOAA there are several dependencies that require items to be implemented in a specific order. The namelist variable for iasi-ng_cads has to be in the gsi and part of the global-workflow before I can add it to the exglobal_analysis.sh script. The next part is the iasi-ng spectral and tau coefficient files have to be available to the global-workflow before I can add the changes to the satinfo file. The global-workflow script exglobal_analysis.sh uses the satifno file to determine which spectral and tau coefficient files to link (copy) into the workspace.

I have a PR open for the global-workflow but it is on hold until the current GSI develop (with or without PR#818) is in the global-workflow.

I know the CRTM tau and spectral coefficient files exist. I have been using them for several months. I have no control over when they are available to the global-workflow.

The fix files for IASI-NG should be ready. I would like to be able to test them with the other pieces in place before submitting the PR. I do not expect any other changes. I can open a PR for the fix files but it has these caveats.

[wx20jjung]

There is a mistake in my previous message it should be PR#815 vice PR#818.

[RussTreadon-NOAA]

Thank you @wx20jjung for the details. I'll stand down and let you and others work through PRs across multiple repos to see these changes get fully into place.