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#2748 (Physical significance of TKE penetration not scaled by the model time step ?) – NEMO

Opened 6 months ago

Last modified 5 months ago

#2748 assigned Request

Physical significance of TKE penetration not scaled by the model time step ?

Reported by: jchanut Owned by: systeam
Priority: low Milestone:
Component: ZDF Version: trunk
Severity: minor Keywords:
Cc:

Description

Context

On TKE additional source term (e.g. nn_etau>0 in namzdf_tke)

Analysis

The additional TKE source term in zdftke is not scaled by the model time step:

      IF( nn_etau == 1 ) THEN           !* penetration below the mixed layer (rn_efr fraction)
         DO_3D_OVR( nn_hls-1, nn_hls-1, nn_hls-1, nn_hls-1, 2, jpkm1 )
            en(ji,jj,jk) = en(ji,jj,jk) + rn_efr * en(ji,jj,1) * EXP( -gdepw(ji,jj,jk,Kmm) / htau(ji,jj) )   &
               &                                 * MAX( 0._wp, 1._wp - zice_fra(ji,jj) ) * wmask(ji,jj,jk) * tmask(ji,jj,1)

As expected, this leads to a dependency of the tke profiles, hence of viscosities/diffusivities on the chosen time step. This may well be on purpose, but I have trouble to see the physical motivation behind that. I would rather have seen a kind of time scale associated with that process (in place of the surface tke fraction) and then multiplied by the time step.

Recommendation

At this point, I would like to be convinced :)

Commit History (0)

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Change History (1)

comment:1 Changed 5 months ago by nemo

  • Owner set to systeam
  • Status changed from new to assigned
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