NCAR / NCAR/DART

Allow the use of RTPS without the need to compute posterior forward operators

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Enhancement inflation
Dominant language
Fortran
Stars
263
Forks
182
Avg merge
11d 12h
Merged PRs (30d)
7

Description

Use case

Use RTPS as posterior inflation without computing posterior forward operators. At the moment, this is not possible. Note that unlike other posterior inflation algorithms in DART, RTPS is not Bayesian and doesn't require forward operator computations.

Is your feature request related to a problem?

Setting posterior inf_flavor to 4 with compute_posterior=.false. generates an error as shown in the adaptive_inflate_mod snippet below:
https://github.com/NCAR/DART/blob/146c853f005568cdc41272e04f5dd85aeb18de74/assimilation_code/modules/assimilation/adaptive_inflate_mod.f90#L470-L475

Describe your preferred solution

I think we can modify the above if statement to exclude RELAXATION_TO_PRIOR_SPREAD from the check.

Describe any alternatives you have considered

N/A

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start in assimilation_code/modules/assimilation/adaptive_inflate_mod.f90 around lines 470-475 and inspect the check triggered by posterior inf_flavor=4 with compute_posterior=.false. Reproduce that configuration and verify that RTPS, identified as RELAXATION_TO_PRIOR_SPREAD, can run without computing posterior forward operators and without the current error.

Written by the indexing model from the issue text.

Assessment

Tech stack
fortran
Domain
data
Issue type
Feature
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
48/100

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