Physics (PBL-SATMEDF) Update for Explicit Subcanopy Effects on Chemical Tracers

[drnimbusrain]

Description

This PR facilitates updates the current integrated subcanopy effect (previously merged PR #928 ) to use a more robust, explicit, 3-layer subcanopy effect on chemical tracers (ONLY) in the ccpp-physics, PBL-SATMEDMF scheme. The vegetative canopy modulates vertical diffusion. We split the diffusion on 3 sub-canopy layers with variable height located at 1, 0.5 and 0.2 canopy height (based on Makar et al. 2017), while ensuring mass conservation before returning to the original model layers (for advection, deposition, other physical processes). This leads to a more pronounced effect on the transport of chemical tracers, particularly those as precursors to near-surface ozone formation in the UFS-AQM configuration.

Issue(s) addressed

#1055

Testing

Tested on GaeaC6 with SRW-App AQM configuration.

Are the changes covered by regression tests?
Yes, AQM regression tests with 'do_canopy' added to UWM.

Have the ufs-weather-model regression test been run? On what platform?
Not yet.

• Will the code updates change regression test baseline?
  N/A

Dependencies

https://github.com/noaa-oar-arl/ufs-weather-model/tree/feature/aqm_canopy_vdf
https://github.com/noaa-oar-arl/ccpp-physics/tree/feature/aqm_canopy_vdf

Do PRs in upstream repositories need to be merged first?
If so add the "waiting for other repos" label and list the upstream PRs
TBD.

@iri01

[gspetro-NOAA]

@grantfirl @dustinswales Could one of you take a look at this PR and give an approval if it seems ready?

[dustinswales]

Looks good to me.
I do have one small question about allocating the fields

[dustinswales]

Thanks for making these changes!

[gspetro-NOAA]

@drnimbusrain The CCPP PR has been merged. Please revert .gitmodules and update the CCPP hash to 9e70979.

[drnimbusrain]

Thank you for the update! Will do

…

On Fri, Feb 27, 2026, 1:41 PM Gillian Petro ***@***.***> wrote: *gspetro-NOAA* left a comment (NOAA-EMC/ufsatm#1056) <#1056 (comment)> @drnimbusrain <https://github.com/drnimbusrain> The CCPP PR has been merged. Please revert .gitmodules and update the CCPP hash to 9e70979 <ufs-community/ccpp-physics@9e70979> . — Reply to this email directly, view it on GitHub <#1056 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AGLFYNWK6WNMHHYWC2K47YT4OCFT5AVCNFSM6AAAAACSKSWRA6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTSNZUGQ3DSNJQGU> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[drnimbusrain]

@gspetro-NOAA OK. .gitmodules reverted and updated ccpp hash.

[gspetro-NOAA]

This PR can be merged. Tests completed successfully on ufs-community/ufs-weather-model#3060. The CCPP sub-PR has been merged, .gitmodules reverted, and CCPP hash updated.