Ice initialization from SST

Versions v4.2.x
1

report for what seems to be bug:
It seems that sea level (zos) is sensitive to initial fields for v4.2.2
Namely:
If the model is initialized with initial fields where temperature is < 2, the sea level drops to some negative value (in my case, -2.5 m). If initialized from some higher temperature initial field, the initial zos was zero.
I’ve managed to trace this “feature” to the step where it seems to be related to ice initialization from SST.
case where:
nn_iceini_file = 0 ! 0 = Initialise sea ice based on SSTs
and further
rn_thres_sst = 2.0 ! max temp. above Tfreeze with initial ice = (sst - tfreeze)

Workaround: Reduce the rn_thres_sst below min(init_temp) for such cases. Alternatively, using a different ice initialization case might work (though I haven’t tested this yet).
… but somethign fishy, worth to look into, is going on in model code :slight_smile:
~i

2

It was done on purpose to “conserve” the total solid+liquid mass at initialization. Hence, this total mass does not depend on the parameters you choose from the namelist. But I am currently thinking about changing that in nemo v5