Opened 8 weeks ago

Closed 6 weeks ago

# supercooling and sea-ice

Reported by:reporter: Owned by:owner: The author of the ticket. Person in charge for handling clem systeam low SI3 release-4.0 major failed no Unspecified

### Description

#### Context

In some configurations the ocean water can be supercooled, especially near ice-shelves.
This is perfectly ok but it can happen that the water remains supercooled all the time. Therefore ice is constantly growing due to turbulent fluxes. If ice is not exported away, then it accumulates until it reaches its max rn_hmax (99m) and then the code crashes.

#### Recommendation

I think we should switch off the turbulent fluxes when we have supercooling and sea ice is very thick. The concept of "very thick" is entirely arbitrary. So, I propose 20m which is already a lot
Here are the lines to add to icethd.F90

```IF( ( t_bo(ji,jj) - ( sst_m(ji,jj) + rt0 ) ) > 0._wp .AND. vt_i(ji,jj) >= 20._wp ) THEN
zqfr     = 0._wp
zqfr_pos = 0._wp
qsb_ice_bot(ji,jj) = 0._wp
ENDIF
```

Or something slightly more complicated with a decrease of the fluxes between 10m and 20m of ice. But I cannot find a proper justification for that

```            IF( ( t_bo(ji,jj) - ( sst_m(ji,jj) + rt0 ) ) > 0._wp ) THEN
IF    ( vt_i(ji,jj) >= 20._wp  ) THEN                           ! v >= 20m then flux = 0
zqfr     = 0._wp
zqfr_pos = 0._wp
qsb_ice_bot(ji,jj) = 0._wp
ELSEIF( vt_i(ji,jj) >= 10._wp .AND. vt_i(ji,jj) < 20._wp ) THEN ! v > 10m and v < 20m then flux = linear transition to 0
zqfr = zqfr * MAX( 0._wp, 2._wp - 0.1_wp * vt_i(ji,jj) )
zqfr_pos = zqfr_pos * MAX( 0._wp, 2._wp - 0.1_wp * vt_i(ji,jj) )
qsb_ice_bot(ji,jj) = qsb_ice_bot(ji,jj) * MAX( 0._wp, 2._wp - 0.1_wp * vt_i(ji,jj) )
ENDIF
ENDIF

```

### Commit History (2)

ChangesetTimeChangeLog
14026clem2020-12-03T09:48:10+01:00

4.0-HEAD: fix bugs and defects related to tickets #2573 #2575 #2576 #2578. Sette passed and those fixes are now in the trunk, so unless there is a tricky trick somewhere, everything should be fine.

13959clem2020-12-01T23:47:44+01:00

multiple adds refering to tickets #2573 #2575 #2576. It concerns small bugs corrections for having a perfectly conservative sea-ice system, plus the removal of restriction on snow layers (one can have several layers in the snow now), plus a bug fix in very peculiar situation where ocean is always supercool

### comment:1 Changed 6 weeks ago by clem

In 13959:

multiple adds refering to tickets #2573 #2575 #2576. It concerns small bugs corrections for having a perfectly conservative sea-ice system, plus the removal of restriction on snow layers (one can have several layers in the snow now), plus a bug fix in very peculiar situation where ocean is always supercool

### comment:2 Changed 6 weeks ago by clem

In 14026:

4.0-HEAD: fix bugs and defects related to tickets #2573 #2575 #2576 #2578. Sette passed and those fixes are now in the trunk, so unless there is a tricky trick somewhere, everything should be fine.

### comment:3 Changed 6 weeks ago by clem

• Resolution set to fixed
• Status changed from new to closed

also in the trunk at r14005

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