! $Id: soilnoxems.f,v 1.7 2006/11/07 19:02:03 bmy Exp $
      SUBROUTINE SNOWNOXEMS(DIRRAD1, DIRRAD2, DIRRAD3, DIRRAD4, DIRRAD5,  
     &           DIRRAD7, DIFRAD1, DIFRAD2, DIFRAD3, DIFRAD4, DIFRAD5, 
     &           DIFRAD6, DIRRAD6, DIFRAD7)
!
!******************************************************************************
!  Subroutine SNOWNOXEMS computes the emission of NOx from the Antarctic snowpack
!  from photodenitrification for the GEOS-CHEM model. (bec, 10/06/11)
!
!  Arguments as Input:
!  ============================================================================
!  (1 ) SUNCOS (REAL*8)     : Array for COSINE( solar zenith angle ) [unitless]
!
!  Other Important variables (mostly via common blocks or F90 modules)
!  ============================================================================
!  (1 ) IJLOOP    (INTEGER) : Grid-box number                 
!  (2 ) JLOP      (INTEGER) : Index to IJLOOP; for a given I,J         
!  (13) SOILTEMP  (REAL*8 ) : Temperature factor (external function) 
!  (14) TMMPK     (REAL*8 ) : Local air temperature (K), w/ diurnal variation       
!  (18) BXHEIGHT  (REAL*8 ) : Grid-box height [m]
!  (19) SNOWNOX   (REAL*8 ) : Output [molec NOx/cm2/s]
!
!  References:
!  ============================================================================
!  (1 ) France et al [2011]                                   
!  (2 ) Frey et al in prep       
!
!  NOTES:
!  (1 ) Be sure to force double precision with the DBLE function and the "D" 
!        exponent, wherever necessary (bmy, 10/6/99)  
!  (2 ) Made JLOP a local variable, so as not to have to reference it from  
!        "comode.h".  "comode.h" should be only for SMVGEAR. (bmy, 10/19/00) 
!  (3 ) Now save soil NOx into GEMISNOX2 array (bdf, bmy, 6/15/01)          
!  (4 ) Replaced IM with IIPAR and JM with JJPAR (bmy, 6/25/02)
!  (5 ) Now reference BXHEIGHT from "dao_mod.f".  Also updated comments and
!        made cosmetic changes. (bmy, 9/18/02)

!******************************************************************************
!
      ! References to F90 modules
      USE DAO_MOD,              ONLY : BXHEIGHT
      USE DAO_MOD,              ONLY : ALBD, LWI, SUNCOS !bec (10/6/11), updated 4/19/2012 mcz
      USE DIAG_MOD,             ONLY : AD32_ph     !bec (10/6/11)
      USE GRID_MOD,             ONLY : GET_XOFFSET, GET_YOFFSET
      USE UVALBEDO_MOD,         ONLY : UVALBEDO  !(mcz 4/24/2012)

      USE CMN_SIZE_MOD             ! Size parameters
      USE CMN_DIAG_MOD             ! Diagnostic switches & arrays
      USE CMN_NOX_MOD              ! GEMISNOX2
      
      IMPLICIT NONE
#     include "define.h" 

      !=============== INPUT PARAMETERS ======================================
      REAL*8,  INTENT(IN) :: DIRRAD1, DIRRAD2, DIRRAD3, DIRRAD4, DIRRAD5 !(mcz 4/24/2012)
      REAL*8,  INTENT(IN) :: DIFRAD1, DIFRAD2, DIFRAD3, DIFRAD4, DIFRAD5 !(mcz 4/24/2012)
      REAL*8,  INTENT(IN) :: DIRRAD6, DIFRAD6, DIRRAD7, DIFRAD7 !(mcz 4/24/2012)


      ! Local variables ======================================================
      INTEGER                       :: I,    J,   L
      INTEGER                       :: IJLOOP, I0, J0
      INTEGER                       :: KBL,  JLOP(IIPAR,JJPAR,1)
      REAL*8                        :: ZBL
      REAL*8                        :: SNOWNOX(IIPAR,JJPAR)
      !REAL*8                        :: SNOWNOXA(IIPAR,JJPAR)
      !REAL*8                        :: SNOWNOXG(IIPAR,JJPAR)

      !=================================================================
      ! SNOWNOXEMS begins here!
      !=================================================================
	write(6,*) 'in SNOWNOXEMS'
      ! Get nested-grid offsets (bmy, 2/11/03)
      I0 = GET_XOFFSET()
      J0 = GET_YOFFSET()

      ! Initalize
      IJLOOP = 0
      DO J = 1, JJPAR
      DO I = 1, IIPAR
         SNOWNOX(I,J)  = 0.D0
         !SNOWNOXA(I,J)  = 0.D0
         !SNOWNOXG(I,J)  = 0.D0
      ENDDO
      ENDDO

      
      !SNOWNOX calculates NOx emissions in [molec NOx/cm2/s]

      !Antarctica and Greenland ========================================
      !DO J = 1, 7 !only compute snow NOx emissions at latitudes south of ~60 deg S
!      DO J = 1, JJPAR
!      DO I = 1, IIPAR

         !IJLOOP is the 1-D grid box index for SUNCOS
!         IJLOOP = ( (J-1) * IIPAR ) + I

!	   IF ( SUNCOS(IJLOOP) > 0.d0 .and. NINT( LWI(I,J) ) == 2  
!     &           .and. UVALBEDO(I,J) == 0.99d0) THEN
	
!        write(6,*) 'in Antarctica and Greenland'
!	   write(6,*) 'SUNCOS = ', SUNCOS(IJLOOP)
!	   write(6,*) 'J = ', J

!        SNOWNOX(I,J) = 5.0d8 !low value from Frey et al. manuscript in prep
!	   ELSE
!        SNOWNOX(I,J) = 0.0d0
!	   ENDIF

!       END DO
!       END DO
     
      !Greenland==================================================================
      !DO J = 38, 45 !roughly latitude and longitude bounds of Greenland
      !DO I = 22, 36 !-71.6 to -11.6 (longitude), 59-85.2N (latitude)

         !IJLOOP is the 1-D grid box index for SUNCOS
         !IJLOOP = ( (J-1) * IIPAR ) + I

	   !IF ( SUNCOS(IJLOOP) > 0.d0 .and. NINT( LWI(I,J) ) == 2  
       !&           .and. UVALBEDO(I,J) == 0.99d0) THEN

        !write(6,*) 'in Greenland'
	!write(6,*) 'SUNCOS = ', SUNCOS(IJLOOP)
	!write(6,*) 'J = ', J 

      	!SNOWNOXG(I,J) = 5.0d8 !low value from Frey et al. manuscript in prep
	   !ELSE
     	!SNOWNOXG(I,J) = 0.0d0
	   !ENDIF
      !==========================================================================


         ! Archive snow NOx emissions [molec NOx/cm2/s]
!         IF ( ND32 > 0 ) THEN
!           AD32_ph(I,J) = AD32_ph(I,J) + SNOWNOX(I,J)
!        ENDIF

         ! Spread NOx emission into the boundary layer
         ! NOTE: BXHEIGHT is in m, so BXHEIGHT * 100 is in cm.
!         ZBL = 0.D0
!         KBL = 1
!         DO L = 1, KBL
!           ZBL = ZBL + BXHEIGHT(I,J,L)*100.D0
!         ENDDO

         ! Store soil NOx in GEMISNOX2, the global NOx emissions array, which
         ! gets passed to SMVGEAR.  GEMISNOX2 has units of [molec NOx/cm3/s].
!         GEMISNOX2(I,J) = GEMISNOX2(I,J) + ( SNOWNOX(I,J) / ZBL )

  	!ENDDO 
	!ENDDO         

      ! Return to calling program
      END SUBROUTINE SNOWNOXEMS