Does meshcap follow the ww3_shel.nml convention for input forcing?

[janahaddad]

@DeniseWorthen @uturuncoglu, as part of troubleshooting oceanmodeling/ufs-weather-model/issues/124 with @yunfangsun @aliabdolali @sbanihash, this question came up: how does the mesh cap handle the input forcing flags in ww3_shel.nml?

is the convention described in ww3_shel.nml read/used by the cap? or is there another primary/first coupled forcing trigger?

[DeniseWorthen]

I'm not entirely clear on the question. The mesh cap reads a WW3 nml file (if it is present, otherwise it will read the older 'inp' file) in the standard WW3 way. The nml setting is used to set some internal WW3 flags like inflags1 etc. I'm not and expert on the inner-workings of those flags w/in WW3.

For example the nml file might have

&input_nml
  input%forcing%winds      = 'C'
  input%forcing%currents   = 'C'
  input%forcing%ice_conc   = 'F'
  input%forcing%ice_param1 = 'F'
  input%forcing%ice_param5 = 'F'
/

The C in the currents setting will make INFLAGS1(2)=.true.. Then in the cap, we make use of the WW3 flags like so:

WW3/model/src/wav_import_export.F90

Lines 352 to 376 in 80a5ad5

	! ---------------
	! INFLAGS1(2) - ocn current fields
	! ---------------
	if (INFLAGS1(2)) then
	TC0 = time0 ! times for ocn current fields
	TCN = timen
	CX0(:,:) = def_value ! ocn u current
	CXN(:,:) = def_value
	if (state_fldchk(importState, 'So_u')) then
	call SetGlobalInput(importState, 'So_u', vm, global_data, rc)
	if (ChkErr(rc,__LINE__,u_FILE_u)) return
	call FillGlobalInput(global_data, CX0)
	call FillGlobalInput(global_data, CXN)
	end if
	CY0(:,:) = def_value ! ocn v current
	CYN(:,:) = def_value
	if (state_fldchk(importState, 'So_v')) then
	call SetGlobalInput(importState, 'So_v', vm, global_data, rc)
	if (ChkErr(rc,__LINE__,u_FILE_u)) return
	call FillGlobalInput(global_data, CY0)
	call FillGlobalInput(global_data, CYN)
	end if
	end if

[aliabdolali]

@DeniseWorthen this is what I thought as well.
If the flag is 'C', the field is read from the coupler while T and F are for reading from file and no forcing. Thanks for your prompt reply.

This is what we discussed and I mentioned it should follow what you described:
In a simulation @yunfangsun reported he is using
input%forcing%winds = 'T'
input%forcing%currents = 'F'
and the model read wind from the coupler, he was not sure about current field.

[aliabdolali]

@josephzhang8 I am adding you here, to use proper flags when you set the coupled case for SCHISM+WW3 test case.

! * The FORCING flag can be : 'F' for "no forcing"
! 'T' for "external forcing file"
! 'H' for "homogeneous forcing input"
! 'C' for "coupled forcing field"

[josephzhang8]

Thx @aliabdolali!
Loop in @danishyo