subroutine avoid2
c
c     +++PURPOSE+++
c     This function prevents the occurence of multiple top frost
c     layers in the soil.  This is a simplification necessary for
c     practicle purposes.  If more than half of the top frost is
c     melted, the top frost is eliminated, otherwise it is
c     assumed that there is no top thaw.
c
c     Author(s):  John Witte, UofMn WCES @ USDA-ARS-NCSRL
c     Date: 04/06/93
c
c     +++ARGUMENT DECLARATIONS+++
c     real
c
c     +++ARGUMENT DEFINITIONS+++
c
c     +++PARAMETERS+++
      include 'pmxpln.inc'
      include 'pmxhil.inc'
      include 'pmxnsl.inc'
c
c     +++COMMON BLOCKS+++
c
      include  'cwint.inc'
c       read:  tfrdp(mxplan),tthawd(mxplan)
c
      include  'cstruc.inc'
c       read:  iplane
c
c     +++END SPECIFICATIONS+++


c XXX Change "gt" to "ge" to be consistent with other limits. dcf 6/94
c     if (tfrdp(iplane) .gt. 0.0001) then
      if (tfrdp(iplane) .ge. 0.0001) then

c -- Then there is no frozen sandwich.

        if ((tthawd(iplane) / tfrdp(iplane)) .gt. 0.5) then

c -- We ignore the top frost layer.

          tthawd(iplane) = 0.0
          tfrdp(iplane)  = 0.0
        else

c -- We assume the top frost goes to the surface.

          tthawd(iplane) = 0.0
        endif
      endif


      return

      end