!-------------------------------------- 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 
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***S/P TWEIGHTS
*
#include "phy_macros_f.h"

      SUBROUTINE TWEIGHTS (ATQ2T,SIGM,SIGT,NI,NJ,NK,LSTAG) 1
*
#include "impnone.cdk"
      INTEGER NI,NJ,NK
      LOGICAL LSTAG
      REAL ATQ2T(NI,NJ),SIGM(NI,NJ),SIGT(NI,NJ)
*
*Author
*          L. Spacek (Dec 2007)
*
*Revision
*
*Object
*          To calculate the linear coefficients for interpolation
*          of temperature/humidity to thermo levels
*
*Arguments
*
*          - Output -
* ATQ2T    coefficients for interpolation of T,Q to thermo levels
*
*          - Input -
* SIGM     sigma momentum levels
* SIGT     sigma thermo levels
* NI       horizontal dimension
* NJ       horizontal dimension
* NK       number of levels
* LSTAG    .true.  model is staggered
*          .false. model is non-staggered
*
**
      INTEGER I, K
*
*
************************************************************************
*     AUTOMATIC ARRAYS
************************************************************************
*
      AUTOMATIC (WRK  ,REAL   ,(NI,NK-1) )
*
**
      IF(LSTAG) THEN
         ATQ2T=0.0
      ELSE
         WRK(:,1:NK-1)=SIGM(:,2:NK)-SIGM(:,1:NK-1)

         CALL VSREC(WRK,WRK,NI*(NK-1))
         DO K=1,NK-1
            DO I=1,NI
               ATQ2T(I,K)=(SIGT(I,K)-SIGM(I,K))*WRK(I,K)
            ENDDO
         ENDDO
         ATQ2T(:,NK)=0.0
      ENDIF
*
      RETURN
      END