module constants_mod ! ! Bruce Wyman ! ! ! ! Defines useful constants for Earth. ! ! ! Constants are defined as real parameters, ! except for PI and RADIAN, which are calculated in constants_init to promote ! consistency and accuracy among various compilers. ! ! Constants are accessed through the "use" statement. ! implicit none private character(len=128) :: version='$Id: constants.f90,v 1.3 2004/12/10 19:35:17 gtn Exp $' character(len=128) :: tagname='$Name: mom4p0d $' !dummy variable to use in HUGE initializations real :: realnumber !------------ physical constants --------------- ! ! radius of the earth ! ! ! rotation rate of the planet (earth) ! ! ! acceleration due to gravity ! ! ! gas constant for dry air ! ! ! RDGAS / CP_AIR ! ! ! specific heat capacity of dry air at constant pressure ! ! ! specific heat capacity taken from McDougall (2002) "Potential Enthalpy ..." ! ! ! average density of sea water ! ! ! reciprocal of average density of sea water ! ! ! (kg/m^3)*(cal/kg/deg C)(joules/cal) = (joules/m^3/deg C) ! real, public, parameter :: RADIUS = 6371.0e3 real, public, parameter :: OMEGA = 7.292e-5 real, public, parameter :: GRAV = 9.80 real, public, parameter :: RDGAS = 287.04 real, public, parameter :: KAPPA = 2./7. real, public, parameter :: CP_AIR = RDGAS/KAPPA real, public, parameter :: CP_OCEAN = 3989.24495292815 real, public, parameter :: RHO0 = 1.035e3 real, public, parameter :: RHO0R = 1.0/RHO0 real, public, parameter :: RHO_CP = RHO0*CP_OCEAN !------------ water vapor constants --------------- ! ! gas constant for water vapor ! ! ! density of liquid water ! ! ! latent heat of evaporation ! ! ! latent heat of fusion ! ! ! latent heat of sublimation ! ! ! temp where fresh water freezes ! real, public, parameter :: RVGAS = 461.50 real, public, parameter :: DENS_H2O = 1000. real, public, parameter :: HLV = 2.500e6 real, public, parameter :: HLF = 3.34e5 real, public, parameter :: HLS = 2.834e6 real, public, parameter :: TFREEZE = 273.16 !-------------- radiation constants ----------------- ! ! molecular weight of air ! ! ! molecular weight of water ! ! ! molecular weight of ozone ! ! ! diffusivity factor ! ! ! seconds in a day ! ! ! Avogadro's number ! ! ! mean sea level pressure ! ! ! mean sea level pressure ! ! ! radius of the earth ! real, public, parameter :: WTMAIR = 2.896440E+01 real, public, parameter :: WTMH2O = 1.801534E+01 real, public, parameter :: WTMO3 = 47.99820E+01 real, public, parameter :: DIFFAC = 1.660000E+00 real, public, parameter :: SECONDS_PER_DAY = 8.640000E+04 real, public, parameter :: AVOGNO = 6.023000E+23 real, public, parameter :: PSTD = 1.013250E+06 real, public, parameter :: PSTD_MKS = 101325.0 real, public, parameter :: REARTH = 6.356766E+08 ! ! factor used to convert flux divergence to heating rate in degrees per day ! ! ! factor used to convert flux divergence to heating rate in degrees per day ! ! ! mixing ratio of molecular oxygen in air ! ! ! reference atmospheric density ! ! ! minimum value allowed as argument to log function ! ! ! melting point of water ! real, public, parameter :: RADCON = ((1.0E+02*GRAV)/(1.0E+04*CP_AIR))*SECONDS_PER_DAY real, public, parameter :: RADCON_MKS = (GRAV/CP_AIR)*SECONDS_PER_DAY real, public, parameter :: O2MIXRAT = 2.0953E-01 real, public, parameter :: RHOAIR = 1.292269 real, public, parameter :: ALOGMIN = -50.0 real, public, parameter :: FREZDK = 273.16 !------------ miscellaneous constants --------------- ! ! Stefan-Boltzmann constant ! ! ! Von Karman constant ! ! ! ratio of circle circumference to diameter ! ! ! degrees per radian ! ! ! converts rho*g*z (in mks) to dbars: 1dbar = 10^4 (kg/m^3)(m/s^2)m ! ! ! degrees Kelvin at zero Celsius ! ! ! a small number to prevent divide by zero exceptions ! real, public, parameter :: STEFAN = 5.6734e-8 real, public, parameter :: VONKARM = 0.40 real, public :: PI = HUGE(realnumber) real, public :: RADIAN = HUGE(realnumber) real, public, parameter :: C2DBARS = 1.e-4 real, public, parameter :: KELVIN = 273.15 real, public, parameter :: EPSLN = 1.0e-40 !----------------------------------------------------------------------- ! version and tagname published ! so that write_version_number can be called for constants_mod by fms_init public :: version, tagname !----------------------------------------------------------------------- public :: constants_init contains subroutine constants_init ! dummy routine. Initialization of PI and RADIAN is done by fms_init. end subroutine constants_init end module constants_mod ! ! ! 1. Renaming of constants. ! ! ! 2. Additional constants. ! ! ! Constants have been declared as type REAL, PARAMETER. ! ! The value a constant can not be changed in a users program. ! New constants can be defined in terms of values from the ! constants module using a parameter statement.

! ! The name given to a particular constant may be changed.

! ! Constants can be used on the right side on an assignment statement ! (their value can not be reassigned). ! ! As PI is calculated, it cannot be a parameter variable. ! Do not assign a new value to PI. ! ! !

!    use constants_mod, only:  TFREEZE, grav_new => GRAV
!    real, parameter :: grav_inv = 1.0 / grav_new
!    tempc(:,:,:) = tempk(:,:,:) - TFREEZE
!    geopotential(:,:) = height(:,:) * grav_new
!

! ! !