function BucketGetSoilMoistCritAmnt() result( OutSoilMoistCritAmnt )


    real(DP) :: OutSoilMoistCritAmnt


    ! 作業変数
    ! Work variables
    !


    ! 初期化確認
    ! Initialization check
    !
    if ( .not. bucket_model_inited ) then
      call MessageNotify( 'E', module_name, 'This module has not been initialized.' )
    end if


!!$    ! 計算時間計測開始
!!$    ! Start measurement of computation time
!!$    !
!!$    call TimesetClockStart( module_name )

    OutSoilMoistCritAmnt = SoilMoistCritAmnt

!!$    ! 計算時間計測一時停止
!!$    ! Pause measurement of computation time
!!$    !
!!$    call TimesetClockStop( module_name )


  end function BucketGetSoilMoistCritAmnt

  subroutine BucketIntegration( xy_FlagOceanGrid, xy_DSoilMoistDt, xy_DSurfSnowDt, xy_SoilMoistB, xy_SurfSnowB, xy_SoilMoistA, xy_SurfSnowA )

    ! 時刻管理
    ! Time control
    !
    use timeset, only: DelTime, TimesetClockStart, TimesetClockStop

    ! 格子点設定
    ! Grid points settings
    !
    use gridset, only: imax, jmax, kmax    ! 鉛直層数.
                               ! Number of vertical level

    logical , intent(in ) :: xy_FlagOceanGrid( 0:imax-1, 1:jmax )
    real(DP), intent(in ) :: xy_DSoilMoistDt ( 0:imax-1, 1:jmax )
    real(DP), intent(in ) :: xy_DSurfSnowDt  ( 0:imax-1, 1:jmax )
    real(DP), intent(in ) :: xy_SoilMoistB   ( 0:imax-1, 1:jmax )
    real(DP), intent(in ) :: xy_SurfSnowB    ( 0:imax-1, 1:jmax )
    real(DP), intent(out) :: xy_SoilMoistA   ( 0:imax-1, 1:jmax )
    real(DP), intent(out) :: xy_SurfSnowA    ( 0:imax-1, 1:jmax )

    ! 作業変数
    ! Work variables
    !
    integer:: i               ! 経度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in longitude
    integer:: j               ! 緯度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in latitude


    ! 初期化確認
    ! Initialization check
    !
    if ( .not. bucket_model_inited ) then
      call MessageNotify( 'E', module_name, 'This module has not been initialized.' )
    end if


    ! 計算時間計測開始
    ! Start measurement of computation time
    !
    call TimesetClockStart( module_name )


    xy_SoilMoistA = xy_SoilMoistB + xy_DSoilMoistDt * 2.0_DP * DelTime

    ! Remove negative values
    !
    do j = 1, jmax
      do i = 0, imax-1
        if( xy_SoilMoistA(i,j) < 0.0_DP ) xy_SoilMoistA(i,j) = 0.0_DP
      end do
    end do

    if ( FlagSnow ) then
      xy_SurfSnowA = xy_SurfSnowB + xy_DSurfSnowDt * 2.0_DP * DelTime

      ! Remove negative values
      !
      do j = 1, jmax
        do i = 0, imax-1
          if( xy_SurfSnowA (i,j) < 0.0_DP ) xy_SurfSnowA (i,j) = 0.0_DP
        end do
      end do
    else
      xy_SurfSnowA = xy_SurfSnowB
    end if


    ! Fill meaningless value in ocean grid
    !
    do j = 1, jmax
      do i = 0, imax-1
        if ( xy_FlagOceanGrid(i,j) ) then
          xy_SoilMoistA(i,j) = SoilMoistMeaningLess
          xy_SurfSnowA(i,j)  = SoilMoistMeaningLess
        end if
      end do
    end do


    ! 計算時間計測一時停止
    ! Pause measurement of computation time
    !
    call TimesetClockStop( module_name )


  end subroutine BucketIntegration

  subroutine BucketModEvapAndLatentHeatFlux( xy_FlagOceanGrid, xy_SoilMoist, xy_SurfSnow, xy_SurfEvapFlux, xy_SurfLatentHeatFlux )

    ! 時刻管理
    ! Time control
    !
    use timeset, only: DelTime, TimesetClockStart, TimesetClockStop

    ! 格子点設定
    ! Grid points settings
    !
    use gridset, only: imax, jmax, kmax    ! 鉛直層数.
                               ! Number of vertical level

    ! 物理定数設定
    ! Physical constants settings
    !
    use constants, only: LatentHeat, LatentHeatFusion
                              ! $ L $ [J kg-1] .
                              ! 融解の潜熱.
                              ! Latent heat of fusion

    logical , intent(in   ) :: xy_FlagOceanGrid     ( 0:imax-1, 1:jmax )
    real(DP), intent(in   ) :: xy_SoilMoist         ( 0:imax-1, 1:jmax )
    real(DP), intent(in   ) :: xy_SurfSnow          ( 0:imax-1, 1:jmax )
    real(DP), intent(inout) :: xy_SurfEvapFlux      ( 0:imax-1, 1:jmax )
    real(DP), intent(inout) :: xy_SurfLatentHeatFlux( 0:imax-1, 1:jmax )


    ! 作業変数
    ! Work variables
    !
    integer:: i               ! 経度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in longitude
    integer:: j               ! 緯度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in latitude


    ! 初期化確認
    ! Initialization check
    !
    if ( .not. bucket_model_inited ) then
      call MessageNotify( 'E', module_name, 'This module has not been initialized.' )
    end if


    ! 計算時間計測開始
    ! Start measurement of computation time
    !
    call TimesetClockStart( module_name )


    if ( FlagSnow ) then
      ! Surface water vapor flux is limited up to the water and snow amount on land. 
      !
      do j = 1, jmax
        do i = 0, imax-1

          if ( .not. xy_FlagOceanGrid(i,j)  ) then
            if ( xy_SurfEvapFlux(i,j) > 0.0_DP ) then
              ! Water vapor flux is positive (transported upward).

              if ( xy_SurfEvapFlux(i,j) * 2.0_DP * DelTime > xy_SoilMoist(i,j) + xy_SurfSnow(i,j)          ) then
                ! All snow and all water is evaporated.
                xy_SurfEvapFlux(i,j) = ( xy_SoilMoist(i,j) + xy_SurfSnow(i,j) ) / ( 2.0_DP * DelTime )
                xy_SurfLatentHeatFlux(i,j) = ( LatentHeat                        * xy_SoilMoist(i,j) + ( LatentHeat + LatentHeatFusion ) * xy_SurfSnow(i,j) ) / ( 2.0_DP * DelTime )
              else if ( xy_SurfEvapFlux(i,j) * 2.0_DP * DelTime > xy_SurfSnow(i,j) ) then
                ! All snow and a part of water is evaporated.
                xy_SurfLatentHeatFlux(i,j) = ( LatentHeat * ( xy_SurfEvapFlux(i,j) * 2.0_DP * DelTime - xy_SurfSnow(i,j) ) + ( LatentHeat + LatentHeatFusion ) * xy_SurfSnow(i,j) ) / ( 2.0_DP * DelTime )
              else
                ! Only a part of snow is evaporated.
                xy_SurfLatentHeatFlux(i,j) = ( LatentHeat + LatentHeatFusion ) * xy_SurfEvapFlux(i,j)
              end if

            else
              ! Water vapor flux is negative (transported downward).

              if ( xy_SurfSnow(i,j) > 0.0_DP ) then
                ! Water vapor is converted to snow. 
                xy_SurfLatentHeatFlux(i,j) = ( LatentHeat + LatentHeatFusion ) * xy_SurfEvapFlux(i,j)
              end if

            end if
          end if

        end do
      end do
    else
      ! Surface water vapor flux is limited up to the water amount on land. 
      !
      do j = 1, jmax
        do i = 0, imax-1
          if ( ( .not. xy_FlagOceanGrid(i,j)                                  ) .and. ( xy_SurfEvapFlux(i,j)                    >  0.0_DP            ) .and. ( xy_SurfEvapFlux(i,j) * 2.0_DP * DelTime >  xy_SoilMoist(i,j) ) ) then
            xy_SurfEvapFlux(i,j) = xy_SoilMoist(i,j) / ( 2.0_DP * DelTime )

            xy_SurfLatentHeatFlux(i,j) = LatentHeat * xy_SoilMoist(i,j) / ( 2.0_DP * DelTime )

          end if
        end do
      end do
    end if

    ! 計算時間計測一時停止
    ! Pause measurement of computation time
    !
    call TimesetClockStop( module_name )


  end subroutine BucketModEvapAndLatentHeatFlux

  subroutine BucketModHumidCoef( xy_FlagOceanGrid, xy_SoilMoist, xy_SurfSnow, xy_SurfHumidCoef )

    ! 格子点設定
    ! Grid points settings
    !
    use gridset, only: imax, jmax, kmax    ! 鉛直層数.
                               ! Number of vertical level

    logical , intent(in   ) :: xy_FlagOceanGrid( 0:imax-1, 1:jmax )
    real(DP), intent(in   ) :: xy_SoilMoist    ( 0:imax-1, 1:jmax )
    real(DP), intent(in   ) :: xy_SurfSnow     ( 0:imax-1, 1:jmax )
    real(DP), intent(inout) :: xy_SurfHumidCoef( 0:imax-1, 1:jmax )


    ! 作業変数
    ! Work variables
    !
    integer:: i               ! 経度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in longitude
    integer:: j               ! 緯度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in latitude

    ! 初期化確認
    ! Initialization check
    !
    if ( .not. bucket_model_inited ) then
      call MessageNotify( 'E', module_name, 'This module has not been initialized.' )
    end if


    ! Surface humidity coefficient is modified.
    !
    if ( FlagSnow ) then
      do j = 1, jmax
        do i = 0, imax-1
          if ( xy_FlagOceanGrid(i,j) ) then
            xy_SurfHumidCoef(i,j) = xy_SurfHumidCoef(i,j)
!!$          else if ( xy_SurfSnow(i,j) > ThresholdSurfSnow ) then
          else if ( xy_SurfSnow(i,j) > HumidCoefSnowThreshold ) then
            xy_SurfHumidCoef(i,j) = 1.0_DP
          else
            xy_SurfHumidCoef(i,j) = xy_SoilMoist(i,j) / SoilMoistCritAmntforEvapEff
            if ( xy_SurfHumidCoef(i,j) > 1.0_DP ) xy_SurfHumidCoef(i,j) = 1.0_DP
          end if
        end do
      end do
    else
      do j = 1, jmax
        do i = 0, imax-1
          if ( xy_FlagOceanGrid(i,j) ) then
            xy_SurfHumidCoef(i,j) = xy_SurfHumidCoef(i,j)
          else
            xy_SurfHumidCoef(i,j) = xy_SoilMoist(i,j) / SoilMoistCritAmntforEvapEff
            if ( xy_SurfHumidCoef(i,j) > 1.0_DP ) xy_SurfHumidCoef(i,j) = 1.0_DP
          end if
        end do
      end do
    end if


  end subroutine BucketModHumidCoef

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

    ! モジュール引用 ; USE statements
    !

    ! 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

    ! 文字列操作
    ! Character handling
    !
    use dc_string, only: StoA

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

    ! ヒストリデータ出力
    ! History data output
    !
    use gtool_historyauto, only: HistoryAutoAddVariable

    ! 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, NmlutilAryValid


    ! 宣言文 ; Declaration statements
    !
    implicit none

    logical, intent(in) :: ArgFlagSnow


    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 /bucket_model_nml/ SoilMoistCritAmnt, SoilMoistCritAmntforEvapEff


    ! 実行文 ; Executable statement
    !

    if ( bucket_model_inited ) return


    FlagSnow = ArgFlagSnow


    ! デフォルト値の設定
    ! Default values settings
    !

    ! Values from Manabe (1969)
    !  Manabe, Climate and the ocean circulation I. The atmospheric circulation and 
    !  the hydrology of the Earth's surface, Mon. Wea. Rev., 97, 739-774, 1969
    !
    SoilMoistCritAmnt            = 1.0e3_DP * 0.15e0_DP
    SoilMoistCritAmntforEvapEff  = 1.0e3_DP * 0.15e0_DP * 0.75e0_DP


    ! NAMELIST の読み込み
    ! NAMELIST is input
    !
    if ( trim(namelist_filename) /= '' ) then
      call FileOpen( unit_nml, namelist_filename, mode = 'r' ) ! (in)

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

      call NmlutilMsg( iostat_nml, module_name ) ! (in)
    end if


!!$    ! ヒストリデータ出力のためのへの変数登録
!!$    ! Register of variables for history data output
!!$    !
!!$    call HistoryAutoAddVariable( 'TempIncByFusion', &
!!$      & (/ 'lon ', 'lat ', 'time' /), &
!!$      & 'temperature increase by fusion', 'K' )


    ! 印字 ; Print
    !
    call MessageNotify( 'M', module_name, '----- Initialization Messages -----' )

    call MessageNotify( 'M', module_name, '  SoilMoistCritAmnt           = %f', d = (/ SoilMoistCritAmnt  /) )
    call MessageNotify( 'M', module_name, '  SoilMoistCritAmntforEvapEff = %f', d = (/ SoilMoistCritAmntforEvapEff /) )
    call MessageNotify( 'M', module_name, '  FlagSnow                    = %y', l = (/ FlagSnow /) )


    bucket_model_inited = .true.

  end subroutine BucketModelInit

  subroutine BucketPRCPAdjust( xy_FlagOceanGrid, xy_SurfRainFlux, xy_SurfSnowFlux, xy_SoilMoist, xy_SurfSnow )

    ! ヒストリデータ出力
    ! History data output
    !
    use gtool_historyauto, only: HistoryAutoPut

    ! 物理定数設定
    ! Physical constants settings
    !
    use constants, only: CpDry, Grav, LatentHeat, LatentHeatFusion
                              ! $ L $ [J kg-1] .
                              ! 融解の潜熱.
                              ! Latent heat of fusion

    ! 時刻管理
    ! Time control
    !
    use timeset, only: DelTime, TimesetClockStart, TimesetClockStop

    ! 格子点設定
    ! Grid points settings
    !
    use gridset, only: imax, jmax, kmax    ! 鉛直層数.
                               ! Number of vertical level

    logical , intent(in   ) :: xy_FlagOceanGrid( 0:imax-1, 1:jmax )
    real(DP), intent(in   ) :: xy_SurfRainFlux ( 0:imax-1, 1:jmax )
    real(DP), intent(in   ) :: xy_SurfSnowFlux ( 0:imax-1, 1:jmax )
    real(DP), intent(inout) :: xy_SoilMoist    ( 0:imax-1, 1:jmax )
    real(DP), intent(inout) :: xy_SurfSnow     ( 0:imax-1, 1:jmax )


    ! 作業変数
    ! Work variables
    !
!!$    real(DP) :: xy_TempIncByFusion( 0:imax-1, 1:jmax )
!!$                              ! Temperature increase by fusion

    integer:: i               ! 経度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in longitude
    integer:: j               ! 緯度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in latitude


    ! 初期化確認
    ! Initialization check
    !
    if ( .not. bucket_model_inited ) then
      call MessageNotify( 'E', module_name, 'This module has not been initialized.' )
    end if


    ! 計算時間計測開始
    ! Start measurement of computation time
    !
    call TimesetClockStart( module_name )


!!$    ! Initialize an array for temperature increase by fusion
!!$    !
!!$    xy_TempIncByFusion = 0.0d0


    if ( FlagSnow ) then
      ! Precipitation is added to soil moisture or surface snow
      !
      do j = 1, jmax
        do i = 0, imax-1

          xy_SoilMoist(i,j) = xy_SoilMoist(i,j) + xy_SurfRainFlux(i,j) * 2.0_DP * DelTime
          xy_SurfSnow (i,j) = xy_SurfSnow (i,j) + xy_SurfSnowFlux(i,j) * 2.0_DP * DelTime

        end do
      end do
    else
      ! Precipitation is added to soil moisture
      !
!!$      xy_SoilMoist = xy_SoilMoist + xy_SurfPRCPFlux * 2.0d0 * DelTime
      xy_SoilMoist = xy_SoilMoist + ( xy_SurfRainFlux + xy_SurfSnowFlux ) * 2.0_DP * DelTime
    end if

    ! Calculation of Run-off
    !
    do j = 1, jmax
      do i = 0, imax-1
        if ( xy_SoilMoist(i,j) > SoilMoistCritAmnt ) xy_SoilMoist(i,j) = SoilMoistCritAmnt
      end do
    end do

    ! Fill meaningless value in ocean grid
    !
    do j = 1, jmax
      do i = 0, imax-1
        if ( xy_FlagOceanGrid(i,j) ) then
          xy_SoilMoist(i,j) = SoilMoistMeaningLess
          xy_SurfSnow (i,j) = SoilMoistMeaningLess
        end if
      end do
    end do

    ! ヒストリデータ出力
    ! History data output
    !
!!$    call HistoryAutoPut( TimeN, 'TempIncByFusion' , xy_TempIncByFusion )

    ! 計算時間計測一時停止
    ! Pause measurement of computation time
    !
    call TimesetClockStop( module_name )

  end subroutine BucketPRCPAdjust

  subroutine BucketSetFlagOceanFromMatthews( xy_SurfType, xy_FlagOceanGrid )
    !
    !
    !
    ! Set flagx for ocean grid point from Matthews' index
    !

    ! モジュール引用 ; USE statements
    !

    ! 格子点設定
    ! Grid points settings
    !
    use gridset, only: imax, jmax, kmax    ! 鉛直層数.
                               ! Number of vertical level

    ! 宣言文 ; Declaration statements
    !
    implicit none

    integer , intent(in ) :: xy_SurfType     (0:imax-1, 1:jmax)
                              ! 土地利用
                              ! Surface index
    logical , intent(out) :: xy_FlagOceanGrid(0:imax-1, 1:jmax)
                              ! 
                              ! Flag for ocean grid


    ! 作業変数
    ! Work variables
    !

    integer:: i               ! 経度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in longitude
    integer:: j               ! 緯度方向に回る DO ループ用作業変数
                              ! Work variables for DO loop in latitude


    ! 実行文 ; Executable statement
    !

    ! 初期化確認
    ! Initialization check
    !
    if ( .not. bucket_model_inited ) then
      call MessageNotify( 'E', module_name, 'This module has not been initialized.' )
    end if


    !
    ! Set index for calculation method
    !
    do j = 1, jmax
      do i = 0, imax-1
        if ( xy_SurfType(i,j) == 0 ) then
          ! ocean
          xy_FlagOceanGrid(i,j) = .true.
        else
          ! land
          xy_FlagOceanGrid(i,j) = .false.
        end if
      end do
    end do


  end subroutine BucketSetFlagOceanFromMatthews