c*************************************************************** 
c this subroutine will calculate the diffusion terms using a 
c mass conserving differencing scheme
c***************************************************************
c   ******  FOR  BASE8A  (new circulation), we have changed q array
c           from 3D to 2D (updated each day)   *********************
c
c  **** NEW for BASE8QH, with diffusion separated from chemistry,
c   Kyy and Kyz are done here, with a 1-day time step, and 
c   Kzz is done in separate, NEWDIFZ routine, with a 3 hour time
c   step for mesospheric diffusion, and all computations for 
c   SUMDIFY,Z,... and SUMTOTY,Z... are commented out since these are
c   just old diagnostics for printout - don't need them anymore ******
C
C   *** AND FOR BASE8SG, Kyz is NOT USED (set = 0.0), so we just have the
C           Kyy calculations here *****


        SUBROUTINE NEWDIFY


#include "com2d.h"


       REAL mhalfy(l$,z$58), kyyh(l$,z$58)


c set up half step diffusion parameters
c this should happen whenever k or m changes

       do 330 IK=1,z$58
       do 330 IJ=1,l$-1
              mhalfy(IJ+1,IK)=(m(IJ,IK)+m(IJ+1,IK))/2.
              kyyh(IJ+1,IK)=(ekyy(IJ,IK)+ekyy(IJ+1,IK))/2.
330     CONTINUE

                                                                ! difny(t$,l$,z$58)
       DO 600 IT=1,ITRANS

       do 900 IK=1,z$58
              term2=1./(rcgs*cos(phi(1))*dphi)*
     c              mhalfy(2,IK)*kyyh(2,IK)/(rcgs)*cos(phih(2))
     c              *(st(IT,2,IK)-st(IT,1,IK))/dphi

              difny(it,1,IK) = -1.*term2

       do 1000 IJ=2,l$-1
              term21=1./(rcgs*cos(phi(IJ))*dphi)*
     c              mhalfy(IJ+1,IK)*kyyh(IJ+1,IK)/(rcgs)*cos(phih(IJ+1))
     c              *(st(IT,IJ+1,IK)-st(IT,IJ,IK))/dphi
              term22=-1./(rcgs*cos(phi(IJ))*dphi)*
     c              mhalfy(IJ,IK)*kyyh(IJ,IK)/(rcgs)*cos(phih(IJ))
     c              *(st(IT,IJ,IK)-st(IT,IJ-1,IK))/dphi
              term2=term21+term22

              difny(it,IJ,IK) = -1.*term2
1000    CONTINUE

              term2=-1./(rcgs*cos(phi(18))*dphi)*
     c              mhalfy(18,IK)*kyyh(18,IK)/(rcgs)*cos(phih(18))
     c              *(st(IT,18,IK)-st(IT,17,IK))/dphi

              difny(it,18,IK) = -1.*term2
900     CONTINUE

600     CONTINUE

	SAVE
	RETURN
	END