ocean_sea_ice_enter_data_impl Subroutine

   subroutine ocean_sea_ice_enter_data_impl(this)
      !! Attach the slot's allocatables to the device.  `copyin` (not
      !! `create`) throughout: every array is host-initialised (0, or
      !! `part_size`/`sal_ice`'s non-zero defaults) at init, and a
      !! restart read seeds the persistent ones host-side before the
      !! mapping.  PR 3c's seam + scratch fields are also `copyin`: they
      !! are host-zeroed at init and (re)filled device-side every thermo
      !! step, so a plain `copyin` is correct (and cheap — one-time).
      !! PR 4b: `u_ice`/`v_ice` are `copyin` (host-zeroed at init, and the
      !! v1 sampler / PR-5 EVP both WRITE them device-side every call —
      !! `copyin` establishes presence, same contract as the `atm_*` seam).
      !! PR 5: `str_d`/`str_t`/`str_s` are `copyin` (host-zeroed at init or
      !! restart-seeded; `ice_evp_dynamics` reads them before the first
      !! write on every call — `limit_stresses` runs first). `tau_a_x`/
      !! `tau_a_y` are `copyin` (host-snapshotted at configure, then read
      !! device-side every substep — never written on-device). `fxoc`/
      !! `fyoc` are `copyin` (host-zeroed at init or restart-seeded; the
      !! EVP core zeros them itself at call entry before accumulating).
      !! PR 63: `tau_ocn_x`/`tau_ocn_y` are `copyin` (host-zeroed at init
      !! or restart-seeded; `ice_tau_mirror_impl` WRITES them device-side
      !! every call to `ice_ocean_stress_flux` — same reasoning as
      !! `fxoc`/`fyoc`). `tau_ocn_valid` is NEVER mapped — it is host-only
      !! scalar state, set on the host by `ice_ocean_stress_flux` and read
      !! on the host by `ice_ocean_stress_resume_apply`; `register_scalar`
      !! forces `device_mapped=.false.` on the restart side for the same
      !! reason.
      !! The transport workspace is `create` (pure scratch, recomputed
      !! from scratch every pass — never read before written), mapped
      !! only `if (this%transport)` (memory Rule 2, same gate as the
      !! host-side allocation).
      type(ocean_sea_ice_t), intent(inout) :: this
      if (.not. this%is_init) return
      !$acc enter data copyin(this%frazil_heat, this%heat_budget_frazil)
      !$acc enter data copyin(this%part_size, this%m_ice, this%m_snow)
      !$acc enter data copyin(this%enth_ice, this%enth_snow, this%sal_ice)
      !$acc enter data copyin(this%m_frozen_diag, this%salt_flux_diag)
      !$acc enter data copyin(this%atm_sf0, this%atm_dsfdt, this%atm_sw_dn, this%atm_fprec)
      !$acc enter data copyin(this%fb, this%sst_seam, this%ssurf_seam, this%tfw_seam)
      !$acc enter data copyin(this%tsurf_out, this%h2o_ocn_to_ice, this%h2o_ice_to_ocn)
      !$acc enter data copyin(this%heat_to_ocn, this%sw_thru, this%snow_to_ice)
      !$acc enter data copyin(this%heat_flux_diag, this%sw_thru_diag, this%m_melt_diag, &
      !$acc&                   this%fprec_ocn_diag)
      !$acc enter data copyin(this%h_lim, this%mh_lim, this%fb_part_sum, this%snow_part_ocn)
      !$acc enter data copyin(this%u_ice, this%v_ice)
      !$acc enter data copyin(this%str_d, this%str_t, this%str_s)
      !$acc enter data copyin(this%tau_a_x, this%tau_a_y)
      !$acc enter data copyin(this%fxoc, this%fyoc)
      !$acc enter data copyin(this%tau_ocn_x, this%tau_ocn_y)
      ! tau_ocn_valid: NEVER mapped (host-only, register_scalar contract).
      if (this%dynamics) call this%evp_ws%enter_data()
      if (this%transport) then
         !$acc enter data create(this%mca_ice, this%mca_snow)
         !$acc enter data create(this%uh_ice, this%vh_ice, this%uh_snow, this%vh_snow)
         !$acc enter data create(this%htot_work, this%hl_x_work, this%hr_x_work)
         !$acc enter data create(this%hl_y_work, this%hr_y_work)
         !$acc enter data create(this%uhtot_work, this%vhtot_work)
         !$acc enter data create(this%tr_flux_x_work, this%tr_flux_y_work)
      end if
   end subroutine ocean_sea_ice_enter_data_impl