Line data    Source code

       1              : !=======================================================================
       2              : 
       3              : ! Ocean boundary interface
       4              : 
       5              :       module icepack_ocean
       6              : 
       7              :       use icepack_kinds
       8              :       use icepack_parameters, only: c0, c1, c1000
       9              :       use icepack_parameters, only: Tffresh, stefan_boltzmann, Lvap, cprho
      10              :       use icepack_warnings, only: warnstr, icepack_warnings_add
      11              :       use icepack_warnings, only: icepack_warnings_setabort, icepack_warnings_aborted
      12              : 
      13              :       implicit none
      14              : 
      15              :       private
      16              :       public :: icepack_ocn_mixed_layer
      17              : 
      18              : !=======================================================================
      19              : 
      20              :       contains
      21              : 
      22              : !=======================================================================
      23              : !=======================================================================
      24              : !autodocument_start icepack_ocn_mixed_layer
      25              : ! Compute the mixed layer heat balance and update the SST.
      26              : ! Compute the energy available to freeze or melt ice.
      27              : ! NOTE: SST changes due to fluxes through the ice are computed in
      28              : !       icepack_therm_vertical.
      29              : 
      30      1972116 :       subroutine icepack_ocn_mixed_layer (alvdr_ocn, swvdr,      &
      31              :                                          alidr_ocn, swidr,      &
      32              :                                          alvdf_ocn, swvdf,      &
      33              :                                          alidf_ocn, swidf,      &
      34              :                                          sst,       flwout_ocn, &
      35              :                                          fsens_ocn, shcoef,     &
      36              :                                          flat_ocn,  lhcoef,     &
      37              :                                          evap_ocn,  flw,        &
      38              :                                          delt,      delq,       &
      39              :                                          aice,      fhocn,      &
      40              :                                          fswthru,   hmix,       &
      41              :                                          Tf,        qdp,        &
      42              :                                          frzmlt,    dt)
      43              : 
      44              :       real (kind=dbl_kind), intent(in) :: &
      45              :          alvdr_ocn , & ! visible, direct   (fraction)
      46              :          alidr_ocn , & ! near-ir, direct   (fraction)
      47              :          alvdf_ocn , & ! visible, diffuse  (fraction)
      48              :          alidf_ocn , & ! near-ir, diffuse  (fraction)
      49              :          swvdr     , & ! sw down, visible, direct  (W/m^2)
      50              :          swvdf     , & ! sw down, visible, diffuse (W/m^2)
      51              :          swidr     , & ! sw down, near IR, direct  (W/m^2)
      52              :          swidf     , & ! sw down, near IR, diffuse (W/m^2)
      53              :          flw       , & ! incoming longwave radiation (W/m^2)
      54              :          Tf        , & ! freezing temperature (C)
      55              :          hmix      , & ! mixed layer depth (m)
      56              :          delt      , & ! potential temperature difference   (K)
      57              :          delq      , & ! specific humidity difference   (kg/kg)
      58              :          shcoef    , & ! transfer coefficient for sensible heat
      59              :          lhcoef    , & ! transfer coefficient for latent heat
      60              :          fhocn     , & ! net heat flux to ocean (W/m^2)
      61              :          fswthru   , & ! shortwave penetrating to ocean (W/m^2)
      62              :          aice      , & ! ice area fraction
      63              :          dt            ! time step (s)
      64              : 
      65              :       real (kind=dbl_kind), intent(inout) :: &
      66              :          flwout_ocn, & ! outgoing longwave radiation (W/m^2)
      67              :          fsens_ocn , & ! sensible heat flux (W/m^2)
      68              :          flat_ocn  , & ! latent heat flux   (W/m^2)
      69              :          evap_ocn  , & ! evaporative water flux (kg/m^2/s)
      70              :          qdp       , & ! deep ocean heat flux (W/m^2), negative upward
      71              :          sst       , & ! sea surface temperature (C)
      72              :          frzmlt        ! freezing/melting potential (W/m^2)
      73              : 
      74              : !autodocument_end
      75              : 
      76              :       ! local variables
      77              : 
      78              :       real (kind=dbl_kind), parameter :: &
      79              :          frzmlt_max = c1000   ! max magnitude of frzmlt (W/m^2)
      80              : 
      81              :       real (kind=dbl_kind) :: &
      82              :          TsfK , & ! surface temperature (K)
      83              :          swabs    ! surface absorbed shortwave heat flux (W/m^2)
      84              : 
      85              :       character(len=*),parameter :: subname='(icepack_ocn_mixed_layer)'
      86              : 
      87              :       ! shortwave radiative flux
      88              :       swabs = (c1-alvdr_ocn) * swvdr + (c1-alidr_ocn) * swidr &
      89      1972116 :             + (c1-alvdf_ocn) * swvdf + (c1-alidf_ocn) * swidf
      90              : 
      91              :       ! ocean surface temperature in Kelvin
      92      1972116 :       TsfK = sst + Tffresh
      93              : 
      94              :       ! longwave radiative flux
      95      1972116 :       flwout_ocn = -stefan_boltzmann * TsfK**4
      96              : 
      97              :       ! downward latent and sensible heat fluxes
      98      1972116 :       fsens_ocn =  shcoef * delt
      99      1972116 :       flat_ocn  =  lhcoef * delq
     100      1972116 :       evap_ocn  = -flat_ocn / Lvap
     101              : 
     102              :       ! Compute sst change due to exchange with atm/ice above
     103              :       sst = sst + dt * ( &
     104              :             (fsens_ocn + flat_ocn + flwout_ocn + flw + swabs) * (c1-aice) &
     105              :           + fhocn + fswthru)         &  ! these are *aice
     106      1972116 :           / (cprho*hmix)
     107              : 
     108              :       ! adjust qdp if cooling of mixed layer would occur when sst <= Tf
     109      1972116 :       if (sst <= Tf .and. qdp > c0) qdp = c0
     110              : 
     111              :       ! computed T change due to exchange with deep layers:
     112      1972116 :       sst = sst - qdp*dt/(cprho*hmix)
     113              : 
     114              :       ! compute potential to freeze or melt ice
     115      1972116 :       frzmlt = (Tf-sst)*cprho*hmix/dt
     116      1972116 :       frzmlt = min(max(frzmlt,-frzmlt_max),frzmlt_max)
     117              : 
     118              :       ! if sst is below freezing, reset sst to Tf
     119      1972116 :       if (sst <= Tf) sst = Tf
     120              : 
     121      1972116 :       end subroutine icepack_ocn_mixed_layer
     122              : 
     123              : !=======================================================================
     124              : 
     125              :       end module icepack_ocean
     126              : 
     127              : !=======================================================================