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user/ctlod/NewSurfaceModule – NEMO
wiki:user/ctlod/NewSurfaceModule

Version 36 (modified by ctlod, 16 years ago) (diff)

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New Surface Module

We put here description of the work done around this package. Mainly some figures ...etc

CONTEXT:
Experiments: REF_CORE (reference version) & SBC_NEW (new surface module)
Configuration type: Configuration ORCA2_LIM with bulk CORE
"Forcing spefs:" precipitation and snow are monthly value without time interpolation else
it will be different in SBC_NEW and REF_CORE.

EXPERIENCES DESCRIPTION:
* FULL_SDP6:
Correction of an other bug in limdyn.F90:
The friction velocity ust2s() is computed at T-point. To do so, we must compute a mean of speed velocities using velocities around T-point at i,j location and not i-1,j-1 location as it is done in the reference.
Color(white,red,'''NOTICE''')?: this run includes the modification done for SDP5. See above.

        ! computation of friction velocity
         DO jj = 2, jpjm1
            DO ji = 2, jpim1

!CT start SDP6
               zu_ice   = u_ice(ji+1,jj+1) - u_oce(ji+1,jj+1)
               zv_ice   = v_ice(ji+1,jj+1) - v_oce(ji+1,jj+1)
!CT SDP6              zu_ice   = u_ice(ji-1,jj-1) - u_oce(ji-1,jj-1)
!CT SDP6              zv_ice   = v_ice(ji-1,jj-1) - v_oce(ji-1,jj-1)
               zt11  = rhoco * ( zu_ice * zu_ice + zv_ice * zv_ice )

               zu_ice   = u_ice(ji,jj+1) - u_oce(ji,jj+1)
               zv_ice   = v_ice(ji,jj+1) - v_oce(ji,jj+1)
!CT SDP6              zu_ice   = u_ice(ji-1,jj) - u_oce(ji-1,jj)
!CT SDP6              zv_ice   = v_ice(ji-1,jj) - v_oce(ji-1,jj)
               zt12  = rhoco * ( zu_ice * zu_ice + zv_ice * zv_ice )

               zu_ice   = u_ice(ji+1,jj) - u_oce(ji+1,jj)
               zv_ice   = v_ice(ji+1,jj) - v_oce(ji+1,jj)
!CT SDP6              zu_ice   = u_ice(ji,jj-1) - u_oce(ji,jj-1)
!CT SDP6              zv_ice   = v_ice(ji,jj-1) - v_oce(ji,jj-1)
               zt21  = rhoco * ( zu_ice * zu_ice + zv_ice * zv_ice )

               zu_ice   = u_ice(ji,jj) - u_oce(ji,jj)
               zv_ice   = v_ice(ji,jj) - v_oce(ji,jj)
               zt22  = rhoco * ( zu_ice * zu_ice + zv_ice * zv_ice )
!CT end SDP6

               ztair2 = gtaux(ji,jj) * gtaux(ji,jj) + gtauy(ji,jj) * gtauy(ji,jj)

!CT start SDP5
               zustm =  0.25 * ( zt11 + zt12 + zt21 + zt22 )
!CT start               zustm =  ( 1 - frld(ji,jj) ) * 0.25 * ( zt11 + zt12 + zt21 + zt22 )        &
!CT start                  &  +        frld(ji,jj)   * SQRT( ztair2 )
!CT start SDP5

               ust2s(ji,jj) = ( zustm / rau0 ) * ( rone + sdvt(ji,jj) ) * tms(ji,jj)
            END DO
         END DO

FULL_SDP5 Experiences:

* FULL_SDP5:
Only for the REF_CORE code, we remove the fraction leads frld in the computation of the friction velocity between sea-ice & ocean in limdyn.F90. It is not necessary to mix since the friction velocity is only used to compute flux at Ice/ocean interface? So:

               ztair2 = gtaux(ji,jj) * gtaux(ji,jj) + gtauy(ji,jj) * gtauy(ji,jj)
!CT start SDP5
               zustm =  0.25 * ( zt11 + zt12 + zt21 + zt22 )
!CT start               zustm =  ( 1 - frld(ji,jj) ) * 0.25 * ( zt11 + zt12 + zt21 + zt22 )        &
!CT start                  &  +        frld(ji,jj)   * SQRT( ztair2 )
!CT start SDP5
               ust2s(ji,jj) = ( zustm / rau0 ) * ( rone + sdvt(ji,jj) ) * tms(ji,jj)

Above, gtau[xy] are wind stress components over the ocean at I-point.
In doing that we are closer to what is done in limdyn.F90 of the NEW SBC.
It results in a sea-ice surface temperature colder O(-1/2°C) than in SDP Ref mainly in the limit sea-ice extent.
And a systematic decrease of the icet thickness by O(-2/4 cm) over all the Arctic reaching in some area O(-10 cm) Hudson bay or near the Bering strait.
So its impact is significant and must be take into account in the rewritten of this part in the NEW _SBC.
Color(white,red,'''BUT''')? it remains a bug in the comptutation of zt11, zt12 ..etc see SDP6 experience below

Ice temperature diffs. between REF_CORE SDP5 - REF_CORE SDP / Year 10 / Winter March:


Ice thickness diffs. between REF_CORE SDP5 - REF_CORE SDP / Year 10 / Winter March:



FULL_SDP4 Experiences:

* FULL_SDP4:
Only for the REF_CORE code, correction of a bug in the computation of the final wind stress in ocesbc.F90 module.

         ! update the stress below sea-ice area
         DO jj = 1, jpjm1
            DO ji = 1, fs_jpim1   ! vertor opt.
!CT start SDP4
               ztx         = MAX( freezn(ji,jj), freezn(ji+1,jj) )
               zty         = MAX( freezn(ji,jj), freezn(ji,jj+1) )
!CT            ztx         = MAX( freezn(ji,jj), freezn(ji,jj+1) )   ! ice/ocean indicator at U- and V-points
!CT            zty         = MAX( freezn(ji,jj), freezn(ji+1,jj) )
!CT end SDP4
               ztaux       = 0.5 *( ftaux(ji+1,jj) + ftaux(ji+1,jj+1) ) ! ice-ocean stress at U- and V-points
               ztauy       = 0.5 *( ftauy(ji,jj+1) + ftauy(ji+1,jj+1) )
               taux(ji,jj) = (1.-ztx) * taux(ji,jj) + ztx * ztaux    ! stress at the ocean surface
               tauy(ji,jj) = (1.-zty) * tauy(ji,jj) + zty * ztauy
            END DO
         END DO

The impact of this modification is weak as seen on plots below change in ice thickness are O(±1/2 cm)) in Arctic during winter (March). Same behaviour in summer (Sept).
Ice thickness diffs. between REF_CORE SDP4 - REF_CORE SDP / Year 10 / Winter March:


Ice thickness diffs. between REF_CORE SDP4 - REF_CORE SDP / Year 10 / Summer September:



FULL_SDP3 Experiences:

* FULL_SDP3:
Only for the SBC_NEW code, this time this run is identical to FULL_SDP but in sbcblk_core.F90, the sea-ice velocity ([uv]i_ice()) has been removed in the computation of the wind stress and wind module over sea-ice.
Since the computation is clearly done in a better way now, it could implies important modifications which should be identify.
Small impact O(±2/3 cm) in the Arctic area but shoul be underlined.

Ice thickness in NEW_SBC experience / Year 10 / Winter March:


Ice thickness in NEW_SBC experience / Year 10 / Summer September:


Ice thickness differences between New SDP3 - New SDP experience / Year 10 / Winter March:
In SDP3 the sea-ice velocity [uv]i_ice() is removed from the computation of sea-ice wind-stress and & scalar wind-stress in sbc_blk_ice() whereas it is used in SDP experience, it is the only thing which changes between the 2
This modification implies a weaker extension off the east Greenland coast and north to the Spitzberg.
A lightly increasing of the ice thickness close to the Greenland and North to the Bering strait area O(+2cm)


Ice thickness differences between NEW_SBC SDP3 - REF_CORE SDP experience / Year 10 / Winter March:
Even with this modification in SDP3, the ice thickness differences are still important O(±10/15 cm) reaching min/max O(±50 cm).
Differences are almost the same than the initial NEW_SBC SDP - REF_CORE SDP see next plot.


Ice thickness differences between NEW_SBC SDP - REF_CORE SDP experience / Year 10 / Winter March:


FULL_SDP2 Experiences:

* FULL_SDP2:
Still SSS damping term without the ice-dynamics, i.e. ln_limdyn=.FALSE. in the sea-ice namelist.

Ice thickness in NEW_SBC experience / Year 10: NO SEA-ICE DYNAMICS = ln_limdyn=FALSE


Ice thickness differences between NEW_SBC & REF_CORE experience / Year 10: NO SEA-ICE DYNAMICS = ln_limdyn=FALSE


FULL_SDP Experiences:

* FULL_SDP:
similar to FULL but with a strong restoring SSS damping of ~ 787 mm/day correponding to 12 days of time restoring
It is the same time damping as the SST which corresponds to -40 W/m2/K used for SST over a 10 meters ocean water column.
Modifications have been necessary in sbcssr.F90 module such as using the array sdta(:,:) computed in dtasal.F90 to ensure same
SSS damping field in both experiments SBC_NEW and REF_CORE.

Ice thickness in NEW_SBC experience / Year 10
The sea-ice extension in winter seems to be larger in this run than in the REF_CORE one.


Ice thickness in REF_CORE experience / Year 10


FULL Experiences:

* FULL: done for REF_CORE and SBC_NEW:
We fully relax constrains imposed in T2X experiences, i.e. on stress, frictional velocity and so on ...

T24 Experience:

* T2X:
In doing the following modifications in both experiments, we are waiting for almost exactly the same results.
# The wind stress ([uv]tau/gtau[xy]) and wind module (zwind_speed_t(:,:)/dUnormt(:,:) at the ocean surface (even
above sea-ice) is forced to be the same in both experiments. (sbcblk_core.F90/flx_core.h90)
# The friction velocity ust2s(:,:) between sea-ice and ocean is also forced to be the same (limdyn.F90)
Ice thickness in NEW_SBC experience / Date 11/2000
Image(T24_Icethic_New_Polaire_112000.png, 90%) Ice thickness differences between NEW_SBC - REF_CORE / Date 11/2000
Image(T24_Icethic_New_T24_Icethic_Ref_Polaire_112000.png, 90%) SSS differences between NEW_SBC - REF_CORE / Date 11/2000
Image(T24_S_New_T24_S_Ref_112000_Global.png, 90%) SST differences between NEW_SBC - REF_CORE / Date 11/2000
Image(T24_T_New_T24_T_Ref_112000_Global.png, 90%) Net heat flux at the sea-ice base differences between NEW_SBC - REF_CORE / Date 11/2000
Image(T24_oceflxb_New_T24_oceflxb_Ref_112000_Global.png, 90%) EmP differences between NEW_SBC - REF_CORE / Date 11/2000
Image(T24_EmP_New_T24_EmP_Ref_112000_gloabl.png, 90%)

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