Ensemble postproc: Allow to not have zero-out variables in the list of increment variables

[shlyaeva]

Description

Allows to not specify zero-out variables in the list of increment variables in the ensemble postprocessing app (they don't need to come from backgrounds or analyses since they are zeroed out anyway!)

This would allow us to run recentering app with LETKF, while recentering analyses that don't have currents around the 3DVar analysis that doesn't have currents. (mom6 IAU requires currents in the increments files).

Manual Testing Instructions (optional)

Specify the currents variables only in set increment variables to zero yaml section in the ensemble postprocessing app in gdas.

Checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have run the unit tests before creating the PR

[guillaumevernieres]

👍

[shlyaeva]

I've pushed a minor update to State::operator+= that allows the increment that's added to the state to have more variables than in the state (those are ignored in this case). This is to handle adding the increment with extra (zeroed-out variables) to the background state.

[Copilot]

Pull request overview

This PR updates the SOCA ensemble analysis postprocessing workflow to support “zero-out” increment variables that are not included in the configured increment variables list, enabling use cases like LETKF recentering when the deterministic analysis lacks certain variables (e.g., currents) that MOM6 IAU still requires in the increment output.

Changes:

• Allow set increment variables to zero to include variables not present in increment variables by expanding each member increment’s allocated fields before zeroing.
• Make soca::State::operator+= skip increment fields that do not exist in the target State (instead of failing), enabling increments to carry extra fields.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/soca/State/State.cc	Skip adding increment fields that aren’t present in the State, with a log message.
src/mains/AnalysisPostproc.h	If zero-out vars aren’t in the increment variable set, allocate them in each increment before calling zero(...).

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