C.......................................................................

C  INCLUDE FILE  CONST.EXT

C  Contains:  Fundamental constants for air quality modeling

C  Dependent Upon:  none

C  Revision History:

C    Adapted 6/92 by CJC from ROM's PI.EXT.

C    3/1/93 John McHenry - include constants needed by LCM aqueous chemistry
C    9/93 by John McHenry - include additional constants needed for FMEM clouds
C    and aqueous chemistry

C    3/4/96 Dr. Francis S. Binkowski - reflect current Models3 view that MKS
C    units should be used wherever possible and that sources be documented.
C    Some variables have been added, names changed, and values revised.

C    3/7/96 - add universal gas constant and compute gas constant in chemical
C    form. TWOPI is now calculated rather than input.

C    3/13/96 - group declarations and parameter statements
C    9/13/96 - include more physical constants
C    12/24/96 - eliminate silly EPSILON, AMISS
C    1/06/97 - eliminate most derived constants - YOJ
C    1/17/97 (comments only) to provide numerical values as reference - DWB

C FSB References:

C      CRC76,        "CRC Handbook of Chemistry and Physics (76th Ed)",
C                     CRC Press, 1995
C      Hobbs, P.V.   "Basic Physical Chemistry for the Atmospheric Sciences",
C                     Cambridge Univ. Press, 206 pp, 1995.
C      Snyder, J.P., "Map Projections-A Working Manual, U.S. Geological Survey
C                     Paper 1395 U.S.GPO, Washington, DC, 1987.
C      Stull, R. B., "An Introduction to Bounday Layer Meteorology", Kluwer,
C                     Dordrecht, 1988
C.......................................................................


C Geometric Constants:

      REAL*8      PI ! pi (single precision 3.141593)
      PARAMETER ( PI = 3.14159265358979324 )

      REAL        PI180 ! pi/180 [ rad/deg ]
      PARAMETER ( PI180  = PI / 180.0 )

C Geodetic Constants:

      REAL        REARTH ! radius of the earth [ m ]
                         ! FSB: radius of sphere having same surface area as
                         ! Clarke ellipsoid of 1866 ( Source: Snyder, 1987)
      PARAMETER ( REARTH = 6370997.0 )

      REAL        SIDAY ! length of a sidereal day [ sec ]
                        ! FSB: Source: CRC76 pp. 14-6
      PARAMETER ( SIDAY = 86164.09 )

      REAL        GRAV ! mean gravitational acceleration [ m/sec**2 ]
                       ! FSB: Value is mean of polar and equatorial values.
                       ! Source: CRC Handbook (76th Ed) pp. 14-6
      PARAMETER ( GRAV = 9.80622 )

      REAL        DG2M ! latitude degrees to meters
      PARAMETER ( DG2M = REARTH * PI180 )

C Solar Constant:
      REAL        SOLCNST ! Solar constant [ W/m**2 ], p14-2 CRC76
      PARAMETER ( SOLCNST = 1373.0 )

C Fundamental Constants: ( Source: CRC76, pp. 1-1 to 1-6)

      REAL        AVO ! Avogadro's Constant [ number/mol ]
      PARAMETER ( AVO = 6.0221367 E23 )

      REAL        RGASUNIV ! universal gas constant [ J/mol-K ]
      PARAMETER ( RGASUNIV = 8.314510 )

      REAL        STDATMPA ! standard atmosphere  [ Pa ]
      PARAMETER ( STDATMPA = 101325.0 )

      REAL        STDTEMP ! Standard Temperature [ K ]
      PARAMETER ( STDTEMP = 273.15 )

      REAL        STFBLZ ! Stefan-Boltzmann [ W/(m**2 K**4) ]
      PARAMETER ( STFBLZ = 5.67051E-8 )

C FSB Non-MKS

      REAL        MOLVOL ! Molar volume at STP [ L/mol ] Non MKS units
      PARAMETER ( MOLVOL = 22.41410 )

C Atmospheric Constants:

      REAL        MWAIR ! mean molecular weight for dry air [ g/mol ]
                        ! FSB: 78.06% N2, 21% O2, and 0.943% A on a mole 
                        ! fraction basis ( Source : Hobbs, 1995) pp. 69-70
      PARAMETER ( MWAIR = 28.9628 )

      REAL        RDGAS  ! dry-air gas constant [ J / kg-K ]
      PARAMETER ( RDGAS = 1.0E3 * RGASUNIV / MWAIR ) ! 287.07548994

      REAL        MWWAT ! mean molecular weight for water vapor [ g/mol ]
      PARAMETER ( MWWAT = 18.0153 )

      REAL        RWVAP ! gas constant for water vapor [ J/kg-K ]
      PARAMETER ( RWVAP = 1.0E3 * RGASUNIV / MWWAT ) ! 461.52492604

C FSB NOTE: CPD, CVD, CPWVAP and CVWVAP are calculated assuming dry air and
C water vapor are classical ideal gases, i.e. vibration does not contribute
C to internal energy.

      REAL        CPD ! specific heat of dry air at constant pressure [ J/kg-K ]
      PARAMETER ( CPD = 7.0 * RDGAS / 2.0 )          ! 1004.7642148

      REAL        CVD ! specific heat of dry air at constant volume [ J/kg-K ]
      PARAMETER ( CVD = 5.0 * RDGAS / 2.0 )          ! 717.68872485

      REAL        CPWVAP ! specific heat for water vapor at constant pressure [ J/kg-K ]
      PARAMETER ( CPWVAP = 4.0 * RWVAP )             ! 1846.0997042

      REAL        CVWVAP ! specific heat for water vapor at constant volume [ J/kg-K ]
      PARAMETER ( CVWVAP = 3.0 * RWVAP )             ! 1384.5747781

      REAL        VP0 ! vapor press of water at 0 C [ Pa ] Source: CRC76 pp. 6-15
      PARAMETER ( VP0 = 611.29 )

C FSB The following values are taken from p. 641 of Stull (1988):

      REAL        LV0 ! latent heat of vaporization of water at 0 C [ J/kg ]
      PARAMETER ( LV0 = 2.501 E6 )

      REAL        DLVDT ! Rate of change of latent heat of vaporization with
                        ! respect to temperature [ J/kg-K ]
      PARAMETER ( DLVDT = 2370.0 )

      REAL        LF0 ! latent heat of fusion of water at 0 C [ J/kg ]
      PARAMETER ( LF0 = 3.34 E5 )

C.......................................................................
