Fix the q2 diagnostics in NoahMP

[CharlesZheZhang]

This PR is to fix the high q2 issue in urban grids in NoahMP, posted here in this thread:
https://forum.mmm.ucar.edu/threads/high-urban-moisture-with-noah-mp-in-mpas-atmosphere-8-2-3.22160/#post-53574

Essentially, the fix is to correct the q2 diagnostics in NoahMP in hotfix-v8.3.1:
in the Noah-MP source file: EnergyVarOutTransferMod.F90
Line 139: MPAS-Model/src/core_atmosphere/physics/physics_noahmp/drivers/mpas/EnergyVarOutTransferMod.F90 at ac3866c1e5b05f6d4f5bd41aeab7d3882bace514 · MPAS-Dev/MPAS-Model
change it to the following:
NoahmpIO%Q2MXY(I) = NoahmpIO%Q2MBXY(I) * ( 1 - NoahmpIO%FVEGXY(I) ) + NoahmpIO%Q2MVXY(I) * NoahmpIO%FVEGXY(I)

I have done a short test with the hotfix-8.3.1 version and with this q2_diag fix, and show this fix will help reduce the high q2 over urban points. please see the figure below:

@cenlinhe @barlage

[cenlinhe]

I confirm that this is a bug and the fix here looks good. This PR for the bug fix needs to be included as soon as possible. This grid-mean Q2 diagnostic calculation is not in the community Noah-MP code version, but added during the Noah-MP coupling with MPAS. This is why we did not notice this in other Noah-MP applications in previous studies.

[abrahamroseman]

I just successful used this correction for my run (v8.3.0):
(I found that v8.3.1 also still has this bug)

[cenlinhe]

Is this bug fix already in the latest MPAS?

[CharlesZheZhang]

Is this bug fix already in the latest MPAS?

No, it is a pull request submitted to hotfix-v8.3.1, but hasn't been merged yet.
I changed the branch name, that's why it's "closed"
I will submit it again.

[cenlinhe]

OK, I see. Thanks. Make sure it is included in your new PR.