Modify physics/drag_suite.F90 to remove topographic limitations on small-scale GWD and TOFD

[mdtoyNOAA]

Description

In earlier tuning exercises with the RAP/HRRR model, two of the GSL drag suite components (in drag_suite.F90): 1) the small-scale gravity wave drag (SSGWD), and 2) turbulent orographic form drag (TOFD), were both limited in strength by imposing limits to orographic variance, and for the TOFD scheme, the e-folding height of 1.5 km was lowered to the height of the PBL under certain cases. Testing with the 3km regional RRFS indicates that these limits should be lifted.

Solution

Testing with the 3km regional RRFS shows that lifting the restrictions on the SSGWD and TOFD schemes improve the 10m windspeed verification in a May 2021 retro test as shown in the attached report (*.pdf). The enhancements are shown by "Experiment 3" in the report.
The code modifications we propose are confined to physics/dragsuite.F90.
RRFS_GWD_retro_results_2021_12_03.pdf

[dustinswales]

@mdtoyNOAA It appears this was addressed in 1195.
Closing this issue. Feel free to reopen if the conversation evolves.