subroutine ConstantsInit
    !
    ! constants モジュールの初期化を行います. 
    ! NAMELIST#constants_nml の読み込みはこの手続きで行われます. 
    !
    ! "constants" module is initialized. 
    ! NAMELIST#constants_nml is loaded in this procedure. 
    !

    ! モジュール引用 ; USE statements
    !

    ! NAMELIST ファイル入力に関するユーティリティ
    ! Utilities for NAMELIST file input
    !
    use namelist_util, only: namelist_filename, NmlutilMsg

    ! ファイル入出力補助
    ! File I/O support
    !
    use dc_iounit, only: FileOpen

    ! 種別型パラメタ
    ! Kind type parameter
    !
    use dc_types, only: STDOUT ! 標準出力の装置番号. Unit number of standard output

    ! メッセージ出力
    ! Message output
    !
    use dc_message, only: MessageNotify

    ! 物理・数学定数設定
    ! Physical and mathematical constants settings
    !
    use constants0, only: PI, GasRUniv

    ! 宣言文 ; Declaration statements
    !
    implicit none

    integer:: unit_nml        ! NAMELIST ファイルオープン用装置番号. 
                              ! Unit number for NAMELIST file open
    integer:: iostat_nml      ! NAMELIST 読み込み時の IOSTAT. 
                              ! IOSTAT of NAMELIST read

    ! NAMELIST 変数群
    ! NAMELIST group name
    !
    namelist /constants_nml/ RPlanet, Omega, Grav, MolWtDry, CpDry, MolWtWet, CpWet, LatentHeat, LatentHeatFusion
          !
          ! デフォルト値については初期化手続 "constants#ConstantsInit" 
          ! のソースコードを参照のこと. 
          !
          ! Refer to source codes in the initialization procedure
          ! "constants#ConstantsInit" for the default values. 
          !

    ! 実行文 ; Executable statement
    !

    if ( constants_inited ) return

    ! デフォルト値の設定
    ! Default values settings
    !
    RPlanet          = 6.371e6_DP
    Omega            = 2.0_DP * PI / ( 60.0_DP * 60.0_DP * 23.9345_DP )

!    Grav             = 9.8_DP    ! old value
    Grav             = 9.80665_DP
                       ! standard acceleration of gravity (m s-2)
                       ! WMO technical regulations (see above)

    CpDry            = 1004.6_DP

!    MolWtDry         = 28.964e-3_DP    ! old value
    MolWtDry         = 28.9644e-3_DP
                       ! WMO technical regulations (see above)

    CpWet            = 1810.0_DP

!    MolWtWet         = 18.01528e-3_DP    ! old value
    MolWtWet         = 18.0153e-3_DP
                       ! WMO technical regulations (see above)

    LatentHeat       = 2.5e6_DP 
    LatentHeatFusion = 334.0d3

    ! NAMELIST からの入力
    ! Input from NAMELIST
    !
    if ( trim(namelist_filename) /= '' ) then
      call FileOpen( unit_nml, namelist_filename, mode = 'r' ) ! (in)

      rewind( unit_nml )
      read( unit_nml, nml = constants_nml, iostat = iostat_nml )   ! (out)
      close( unit_nml )

      call NmlutilMsg( iostat_nml, module_name ) ! (in)
      if ( iostat_nml == 0 ) write( STDOUT, nml = constants_nml )
    end if

    GasRDry          = GasRUniv / MolWtDry
    GasRWet          = GasRUniv / MolWtWet
    EpsV             = MolWtWet / MolWtDry


    ! 印字 ; Print
    !
    call MessageNotify( 'M', module_name, '----- Initialization Messages -----' )
    call MessageNotify( 'M', module_name, '  RPlanet          = %f', d = (/ RPlanet          /) )
    call MessageNotify( 'M', module_name, '  Omega            = %f', d = (/ Omega            /) )
    call MessageNotify( 'M', module_name, '  Grav             = %f', d = (/ Grav             /) )

    call MessageNotify( 'M', module_name, '  CpDry            = %f', d = (/ CpDry            /) )
    call MessageNotify( 'M', module_name, '  MolWtDry         = %f', d = (/ MolWtDry         /) )

    call MessageNotify( 'M', module_name, '  CpWet            = %f', d = (/ CpWet            /) )
    call MessageNotify( 'M', module_name, '  MolWtWet         = %f', d = (/ MolWtWet         /) )
    call MessageNotify( 'M', module_name, '  LatentHeat       = %f', d = (/ LatentHeat       /) )
    call MessageNotify( 'M', module_name, '  LatentHeatFusion = %f', d = (/ LatentHeatFusion /) )

    call MessageNotify( 'M', module_name, '  GasRDry          = %f', d = (/ GasRDry          /) )
    call MessageNotify( 'M', module_name, '  GasRWet          = %f', d = (/ GasRWet          /) )
    call MessageNotify( 'M', module_name, '  EpsV             = %f', d = (/ EpsV             /) )
    call MessageNotify( 'M', module_name, '  FKarm            = %f', d = (/ FKarm            /) )
    call MessageNotify( 'M', module_name, '-- version = %c', c1 = trim(version) )

    constants_inited = .true.

  end subroutine ConstantsInit