Change default value of fractional_seaice from 0 to 1

[weiwangncar]

Breaks several regression tests

em_real 60NE MPI (serial and openmp are OK)

moving nest case 01 MPI

openmp b4b broken with 07NE, 20, 20NE, 60, 71, 78, tropical

TYPE: enhancement

KEYWORDS: namelist fractional_seaice, default

SOURCE: Internal

DESCRIPTION OF CHANGES:
Since GFS, the most commonly used input data source, has been providing fractional seaice
data for a while, it seems reasonable to make the default option for fractional_seaice to be 1.
This should also help our general users. Both ERA5 and ERA-Interim provide fractional seaice
data, too.

LIST OF MODIFIED FILES:
M Registry/Registry.EM_COMMON

TESTS CONDUCTED:
Reg test:

RELEASE NOTE: The default option for using fractional_seaice has been changed from 0 (off) to 1 (on) starting with release v4.2.

[davegill]

@weiwangncar
Wei,
Changing this default causes some troubles.

-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE:  <stdin>  LINE:    2317
SLAB scheme cannot be used with fractional seaice
-------------------------------------------

Please add either

1. a check_a_mundo test that turns off the fractional seaice if the LSM is the slab model
2. or a trapped fatal error in check_a_mundo (so that we do not have to do them one at a time via physics_init)

[davegill]

@weiwangncar
Wei,
This mod breaks the regression test, as there are a number of sf_surface_physics=1 options for the em_real cases. I need to put in the fractional_seaice = 0 for all of those. Until then, with this mod, there will be about 30 FAILs.

[davegill]

@weiwangncar
Wei,
It also seems that PX does not always work well with fractional_seaice. Maybe due to the moisture nudging?

[davegill]

Replaced by: Change default fractional_seaice option from 0 to 1 (#1401)