[MITgcm-devel] another bug in growth.F ?

[Dimitris Menemenlis]

Martin,

> Thanks for sorting these things out (and checking them in). I am looking
> forward to trying them out.

Not sure if things are fully sorted out yet.  Jinlun's HSNOW fix still blows up
tangent-linear sensitivity

> As a first impression from my 2x2 degree simulation, your changes to growth.F
> dramatically increases seaice thickness in the southern ocean (and also snow
> thickness), further, snow is only where there is ice (good), and my Weddell
> Gyre is much better represented now.

Technically what that bit of code is trying to do is to use any residual heat in 
the surface level temperature, i.e., if surface level temperature is still above 
sea-ice freezing point after melting all the sea ice, to melt any residual
snow.  So overall I expect surface water to be a bit colder and fresher than 
without this fix, which is consistent with thicker sea-ice and thicker snow over 
that sea ice, if does not completely melt in the summer.

But most Antarctic sea ice does melt during southern hemisphere summer, so there 
should not be more than a year's worth of accumulation in most places.

But why is the tangent linear still so sensitive?

In the hi-res cube-sphere tests should I turn on HSNOW advection?  Is that code 
fairly robust and debugged now?

Cheers, Dimitris