snowmelt__original.F90

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module snowmelt__original
 
  use iso_c_binding, only   : c_int, c_float, c_double, c_bool
  implicit none
 
  private
 
  public :: snowmelt_original_calculate
 
  real (c_double), parameter    :: freezing_f    = 32.0_c_double
  real (c_double), parameter    :: freezing_c    = 0.0_c_double
  real (c_double), parameter    :: melt_index    = 1.5_c_double
  real (c_double), parameter    :: degc_per_degf = 0.55555555555555555555556_c_double
  real (c_double), parameter    :: mm_per_inch   = 25.4_c_double
 
contains
 
  elemental subroutine snowmelt_original_calculate( potential_snowmelt, tmin, tmax, imperial_units )
 
    real (c_float), intent(inout)      :: potential_snowmelt 
    real (c_float), intent(in)         :: tmin
    real (c_float), intent(in)         :: tmax
    logical ( c_bool), intent(in)      :: imperial_units
 
    if ( imperial_units ) then
 
      !> temperatures in degrees Fahrenheit, snowmelt in inches
 
      ! Vic's port of Wes's code simply tests to see whether the 
 
      ! from Vic's earliest port of Wes's code: (TMax in Fahrenheit)
      ! 1.5 * (5_T_INT * ( cel%rTMax - rFREEZING) / 228.6)
 
      if ( ( ( tmin + tmax ) / 2.0_c_double ) > freezing_f ) then
 
        potential_snowmelt = melt_index * ( tmax - freezing_f ) * degc_per_degf / mm_per_inch
 
      else 
 
        potential_snowmelt = 0.0_c_float
 
      end if
 
    else
 
      !> temperatures in degrees Celcius, snowmelt in mm
 
      if ( ( ( tmin + tmax ) / 2.0_c_double ) > freezing_c ) then
 
        potential_snowmelt = melt_index * tmax 
 
      else 
 
        potential_snowmelt = 0.0_c_float
 
      end if
 
    endif  
 
  end subroutine snowmelt_original_calculate
 
end module snowmelt__original