[MITgcm-devel] problem in seaice_lsr with cubed sphere

[Martin Losch]

Hi again,

after playing a little, it seems there are more problems than just the zero recip_raw/ras, so it may be easier to just include a resetting of zero BU/BV at the end of the routine (although this may cover up unrecognized problems).

Since this all of this is sufficiently fragile, I’d like to add the new capabilitiies: RAS and strong implicit coupling in one of the test experiments. How about global_ocean.cs32x15/input.seaice ?

Martin

On Dec 2, 2014, at 11:55 AM, Martin Losch <Martin.Losch at awi.de> wrote:

> Hi Jean-Michel,
> 
> yesterday I implemented the option to compute the LSR solution on overlapping tiles, i.e. a restricted additive schwarz (RAS) method. imin/imax can be 1-SEAICE_OLx/sNx+SEAICE_OLx etc. This works fine for SEAICE_OLx <= OLx-2 on simple domains, but for cubed sphere experiments, I need to set SEAICE_OLx=OLx-3 for this to work. SEAICE_OLx = OLx-2 (=2) I get NaN in global_ocean.cs32x15.seaice (and others that use LSR), in the second linear iteration of the solver. 
> The reason seems to be BU=0 in some of the corner halos (34,18,2,1), and this is because recip_raw(34,18,2,1) seems to be zero.
> 
> Can you reproduce this problem (set SEAICE_OLx=2, and SEAICE_OLy = 2 in global_ocean.cs32x15/input.seaice/data.seaice and run ./testreport -t global_ocean.cs32x15)?
> Can we find a decent way to fix that? Initialise recip_raw=1 always? or do I have to check my BU/BV and reset them if they are zero?
> 
> Martin
> 
> 
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