RRFS cloud base/top: diagnose using cloud fraction

[jaymes-kenyon]

This code updates the cloud-base and cloud-top height (and pressure) diagnostics for RRFS applications, addressing issue #790. Rather than using explicit (grid-scale) cloud water and ice, the proposed code uses the cloud fraction provided by the model.

• For cloud-base height (and pressure), the code searches upward, then locates the model mid-layer point where cloud fraction is >= 2%. The underlying interface level is then assigned as the cloud base.
• For cloud-top height (and pressure), the search proceeds downward. However, the model mid-layer point is retained as the cloud top, rather then the overlying interface level.

This code has been tested in a RRFS case and produces satisfactory results. Thanks to @joeolson42 (NOAA / GSL / EPAD / Model Physics Branch) for the collaboration.

[WenMeng-NOAA]

The UPP RT on Hera indicate the following changes:

fv3r(rrfs): 
NATLEV--
1614:1346818648:PRES:cloud base:rpn_corr=0.670028:rpn_rms=62502.5
1615:1349115561:HGT:cloud base:rpn_corr=0.365044:rpn_rms=5670.54
1616:1351360814:PRES:grid scale cloud bottom level:rpn_corr=0.671265:rpn_rms=62155.3
1617:1353662250:PRES:cloud top:rpn_corr=0.617659:rpn_rms=54259.6
1618:1355736553:HGT:cloud top:rpn_corr=0.617302:rpn_rms=6871.4
1619:1357903926:TMP:cloud top:rpn_corr=0.598246:rpn_rms=371.684
1620:1359887723:PRES:grid scale cloud top level:rpn_corr=0.617659:rpn_rms=54259.6

PRSLEV--
893:847611164:PRES:cloud base:rpn_corr=0.670028:rpn_rms=62502.5
894:849908077:HGT:cloud base:rpn_corr=0.365044:rpn_rms=5670.54
898:858689763:PRES:grid scale cloud bottom level:rpn_corr=0.671265:rpn_rms=62155.3
899:860991199:PRES:cloud top:rpn_corr=0.617659:rpn_rms=54259.6
900:863065502:HGT:cloud top:rpn_corr=0.617302:rpn_rms=6871.4
901:865232875:TMP:cloud top:rpn_corr=0.598246:rpn_rms=371.684
903:868039118:PRES:grid scale cloud top level:rpn_corr=0.617659:rpn_rms=54259.6

3drtma:
NATLEV--
1614:1299926568:PRES:cloud base:rpn_corr=0.481097:rpn_rms=78085.8
1615:1302511707:HGT:cloud base:rpn_corr=0.331731:rpn_rms=5672.06
1616:1305069244:PRES:grid scale cloud bottom level:rpn_corr=0.482067:rpn_rms=77580.7
1617:1307659749:PRES:cloud top:rpn_corr=0.406446:rpn_rms=69175.5
1618:1310167527:HGT:cloud top:rpn_corr=0.442935:rpn_rms=7134.64
1619:1312722741:TMP:cloud top:rpn_corr=0.438933:rpn_rms=462.415
1620:1315052114:PRES:grid scale cloud top level:rpn_corr=0.406446:rpn_rms=69175.5

PRSLEV--
893:835275641:PRES:cloud base:rpn_corr=0.481097:rpn_rms=78085.8
894:837860780:HGT:cloud base:rpn_corr=0.331731:rpn_rms=5672.06
898:846923435:PRES:grid scale cloud bottom level:rpn_corr=0.482067:rpn_rms=77580.7
899:849513940:PRES:cloud top:rpn_corr=0.406446:rpn_rms=69175.5
900:852021718:HGT:cloud top:rpn_corr=0.442935:rpn_rms=7134.64
901:854576932:TMP:cloud top:rpn_corr=0.438933:rpn_rms=462.415
903:857676827:PRES:grid scale cloud top level:rpn_corr=0.406446:rpn_rms=69175.5

hafs:
HURPRS--
725:784488845:TMP:cloud top:rpn_corr=0.494309:rpn_rms=431.326

[WenMeng-NOAA]

@jaymes-kenyon I would think all changes from my UPP RT (see above) are expected results. You may access the test case for RRFS on Hera at
/scratch1/NCEPDEV/stmp2/Wen.Meng/fv3r_2023062800. Please let me know if you see issues.

[WenMeng-NOAA]

@BinLiu-NOAA and @LinZhu-NOAA There will be changes in cloud top temperature for hafs products with updates of cloud base/top height calculation for all regional FV3 models (See my testing above) in this PR. Please let me know if you have concerns.

[jaymes-kenyon]

Thanks, @WenMeng-NOAA — these results would be expected. Indeed, changes in cloud-top height (via the ITOP value) will also produce changes in cloud-top temperature. This occurs at line 2644 in CLDRAD.f.

[WenMeng-NOAA]

Thanks, @WenMeng-NOAA — these results would be expected. Indeed, changes in cloud-top height (via the ITOP value) will also produce changes in cloud-top temperature. This occurs at line 2644 in CLDRAD.f.

@jaymes-kenyon Thanks for confirming.

[WenMeng-NOAA]

@FernandoAndrade-NOAA I completed the UPP RT on Hera at /scratch1/NCEPDEV/stmp2/Wen.Meng. You may copy the new baselines for Hera and start the RT on Orion.

[FernandoAndrade-NOAA]

@FernandoAndrade-NOAA I completed the UPP RT on Hera at /scratch1/NCEPDEV/stmp2/Wen.Meng. You may copy the new baselines for Hera and start the RT on Orion.

Understood thank you. I'll get started on updating Hera BLs. Orion is currently down for maintenance, I'll run RTs when it's available later this afternoon.

[FernandoAndrade-NOAA]

Orion RTs have completed with the same changes in results for 3drtma, fv3r, and hafs, baselines will be updated for these tests on Orion. Hera BLs have been updated.

[WenMeng-NOAA]

This PR is ready for merging.