anchor.diff:      use module_mp_wsm6,             only: wsm6, wsm6init
       use module_mp_simple,           only: mp_simple_driver
       use mod_wrf_constants !,          only: rhoair0, rhowater, rhosnow, cliq, cpv
  +    use time,                       only: calc_year_fraction
       implicit none
   
       ! permit the microphysics to update on a longer time step than the advection
  
positive.code:     !!
      !!----------------------------------------------------------
      subroutine distribute_precip(current_precip, last_precip, local_fraction, precip_delta)
          real, dimension(:,:), intent(inout) :: current_precip, last_precip
          real, intent(in) :: local_fraction
          logical, intent(in) :: precip_delta
  
negative.code:         if (precip_delta) then
              do j=2,ny-1
                  do i=2,nx-1
                      this_precip(i,j)    = current_precip(i,j)-last_precip(i,j)
                      current_precip(i,j) = last_precip(i,j)
                  end do
              end do
          else
              do j=2,ny-1
                  do i=2,nx-1
                      this_precip(i,j)    = last_precip(i,j)
                      current_precip(i,j) = current_precip(i,j)-last_precip(i,j)
                  end do
              end do
  