turning RRTMG-P on by default in CAM7 + some namelist defaults

[cecilehannay]

Issue Type

Other (please describe below)

Issue Description

We would like to turn RRTMG-P on by default in CAM7.

We are also using some namelist changes:

We want to keep the correct radiative property for mam4_mode3 when running with RRTMGP. It was a bug and it was reported already. But if RRTMGP becomes the default, we want to make sure this is fixed:

M:mam4_mode3:/glade/campaign/cesm/cesmdata/inputdata/atm/cam/physprops/mam4_mode3_rrtmg_aeronetdust_c141106.nc

Other changes:

• We need to have a ubc_file_path allowing to full 20th century period. I saw emails about this from Bill and Francis.

ubc_file_path=  /glade/campaign/cesm/cesmdata/inputdata/atm/cam/chem/ubc/b.e21.BWHIST.f09_g17.CMIP6-historical-WACCM.ensAvg123.cam.h0zm.H2O.1849-2014_c240604.nc

• I think we want to change the seasalt_emis_scale to:

 seasalt_emis_scale             = 0.75D0 

Will this change answers?

Yes

Will you be implementing this yourself?

No

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@PeterHjortLauritzen, @cacraigucar, @tilmes