dallaston2015_salt Function

  function dallaston2015_salt(this) result(salt)
    class(dallaston2015_melt), intent(in) :: this
    class(scalar_field), pointer          :: salt
      !! The value of the contribution made by melting/thermal
      !! transfer to the salt equation for a [[plume]]
    if (.not. allocated(this%melt_values)) error stop ('Melt values not allocated')
    call this%melt_values%allocate_scalar_field(salt)
    salt = this%melt_conversion/this%salinity_denom * this%melt_values
  end function dallaston2015_salt