!-------------------------------------- LICENCE BEGIN ------------------------------------
!Environment Canada - Atmospheric Science and Technology License/Disclaimer,
!                     version 3; Last Modified: May 7, 2008.
!This is free but copyrighted software; you can use/redistribute/modify it under the terms
!of the Environment Canada - Atmospheric Science and Technology License/Disclaimer
!version 3 or (at your option) any later version that should be found at:
!http://collaboration.cmc.ec.gc.ca/science/rpn.comm/license.html
!
!This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
!without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
!See the above mentioned License/Disclaimer for more details.
!You should have received a copy of the License/Disclaimer along with this software;
!if not, you can write to: EC-RPN COMM Group, 2121 TransCanada, suite 500, Dorval (Quebec),
!CANADA, H9P 1J3; or send e-mail to service.rpn@ec.gc.ca
!-------------------------------------- LICENCE END --------------------------------------
!


      SUBROUTINE MONOTONIC_INVERSION (NINV, tg,tt,gz,nlev,lev) 2

#if defined (DOC)
!***********************************************************************
!
!**ID MONOTONIC_INVERSION -- DETECT TEMPERATURE INVERSION
!
!       SCIENCE:  L. GARAND AND S. NADON
!       AUTHOR:   A. BEAULNE (CMDA/SMC)      June 2004
!                 A. BEAULNE (CMDA/SMC)     March 2006  (ADAPT TO 3DVAR)                 
!
!       REVISION:
!
!       OBJECT:   DETERMINE IF THERE IS A PRESENCE (NINV=1) OR NOT (NINV=0)
!           OF A TEMPERATURE INVERSION GOING FROM THE SURFACE UP TO THE
!           HEIGHT LEV
!
!       ARGUMENTS:
!          INPUT:
!            -TG       : SKIN TEMPERATURE (DEG K)
!            -TT(NLEV) : TEMPERATURE PROFILE (DEG K)
!            -GZ(NLEV) : HEIGHT PROFILE ABOVE GROUND (M)
!            -NLEV     : NUMBER OF VERTICAL LEVELS
!            -LEV      : HEIGHT TO SEARCH FOR TEMPERATURE INVERSION (M)
!
!          OUTPUT:
!            -NINV     : PRESENCE (1) OR NOT (0) OF A TEMPERATURE INVERSION
!                         FROM THE SURFACE TO HEIGHT LEV
!
!
!***********************************************************************
#endif


      IMPLICIT NONE

      INTEGER   :: NINV,NL,NLEV
      REAL(8)   :: LEV,TG,TT(NLEV),GZ(NLEV)


      NINV = 0
      IF ( TG - TT(NLEV) < 0. ) THEN
        NINV = 1
        DO NL = NLEV-1, 1, -1
          IF ( GZ(NL) > LEV ) EXIT
          IF ( TT(NL+1) - TT(NL) > 0. ) THEN
            NINV = 0
            EXIT
          END IF
        END DO
      END IF


      END SUBROUTINE MONOTONIC_INVERSION