[ww3_multi] Negative UNIT number for ASCII output

[ukmo-ccbunney]

Describe the bug
When compiling ww3_multi with the ASCII switch, the unit number for ASCII gridded output (w3iogo) is being set to -1

To Reproduce
Run mww3_test_09/MPI_ASCII regtest; model core dumps trying to open output file.
Issue is likely compiler dependent.

I am getting the issue when using the GNU GFortran compiler and a bit of debug PRINT statements shows that the unit number for NDSOA is -1 for ASCII output here, which is invalid:

WW3/model/src/w3iogomd.F90

Lines 2621 to 2624 in 4cd995d

	#ifdef W3_ASCII
	OPEN (NDSOA,FILE=FNMPRE(:J)//'out_grd.'//FILEXT(:I)//'.txt', &
	form ='FORMATTED',ERR=800,IOSTAT=IERR)
	#endif

I am not sure how the unit numbers are set in WW3_MULTI, I will investigate.

Expected behavior
Core dump.
Error message I get is:

8  0x52D40F in __w3servmd_MOD_extcde at w3servmd.F90:867
#9  0x4D26C0 in __w3iogomd_MOD_w3iogo at w3iogomd.F90:4042
#10  0x544B23 in __w3wavemd_MOD_w3wave at w3wavemd.F90:2599
#11  0x44912C in __wmwavemd_MOD_wmwave at wmwavemd.F90:1286
#12  0x4012F2 in w3mlti at ww3_multi.F90:190

 *** WAVEWATCH III ERROR IN W3IOGO :
     ERROR IN OPENING FILE
     IOSTAT = 5002


EXTCDE MPI_ABORT, IEXIT=    41

[ukmo-ccbunney]

I think it perhaps needs an extra entry like this in wminitmd to set the unit number for ASCII out_grd output?

WW3/model/src/wminitmd.F90

Lines 5448 to 5456 in 4cd995d

	IF ( MDS(7,I) .NE. -1 ) THEN
	IF ( IAPROC .EQ. NAPFLD ) THEN
	TNAME = TRIM(FNMPRE)//'out_grd.' // FILEXT(:II)
	CALL WMUSET ( MDSE,MDST, MDS(7,I), .TRUE., NAME=TNAME )
	ELSE
	CALL WMUSET ( MDSE,MDST, MDS(7,I), .FALSE. )
	MDS(7,I) = -1
	END IF
	END IF

[MatthewMasarik-NOAA]

I think it perhaps needs an extra entry like this in wminitmd to set the unit number for ASCII out_grd output?

WW3/model/src/wminitmd.F90

Lines 5448 to 5456 in 4cd995d

	IF ( MDS(7,I) .NE. -1 ) THEN
	IF ( IAPROC .EQ. NAPFLD ) THEN
	TNAME = TRIM(FNMPRE)//'out_grd.' // FILEXT(:II)
	CALL WMUSET ( MDSE,MDST, MDS(7,I), .TRUE., NAME=TNAME )
	ELSE
	CALL WMUSET ( MDSE,MDST, MDS(7,I), .FALSE. )
	MDS(7,I) = -1
	END IF
	END IF

Interesting. That looks promising.

[ukmo-ccbunney]

OK. I think I have a fix for this.
The unit number assignment in ww3_multi is much more complex than I realised!
I will raise a PR after running some tests.