SUBROUTINE GRADIN

      IMPLICIT NONE
      INCLUDE 'champ.cdk'
      INCLUDE 'chinc.cdk'
      INCLUDE 'chobs.cdk'

      REAL KX,KY,KW

      DO IKX=1,IKTX
       KX = FLOAT(IKX-1) 
       DO IKY=1,IKTY
        KY = FLOAT(IKY - KTY - 1)
        NZK(IKX,IKY) = CMPLX(0.,0.)
        NSK(IKX,IKY) = CMPLX(0.,0.)
        IF ( L(IKX+KTX,IKY).NE.1 ) GO TO 30
        KW = MAX(KX*KX+KY*KY ,0.001 ) 
        NZK(IKX,IKY) = ZTRA2(IKX,IKY,NT+2)
C+        NZK(IKX,IKY) =
C+     .     (ZT(IKX,IKY)+ZTRA2(IKX,IKY,NT+2)-ZOBS(IKX,IKY,NT+2))
C+     .               *  PZ(IKX,IKY,NT+2)

c        NSK(IKX,IKY) =
c     .     (ST(IKX,IKY)+STRA2(IKX,IKY,NT+2)-SOBS(IKX,IKY,NT+2))
c     .               *  PS(IKX,IKY,NT+2)
C        NZK(IKX,IKY) = NZK(IKX,IKY)/KW**2
        NSK(IKX,IKY) = NSK(IKX,IKY)
 30    ENDDO
      ENDDO

      RETURN
      END