[Mitgcm-support] Re: pkg/seaice and pkg/exf

[mitgcm-support at dev.mitgcm.org]

Hi Dimitris, 

A couple of pickup issues: 

(i) when pickup.chkptA is written, there's no pickup_seaice.chkptA.

(ii) Also, I get:

PGFIO-F-253/unformatted read/unit=9/attempt to read non-existent record
(direct access).
 File name = pickup_seaice.0000026280    unformatted, direct access
record = 1596
 In source file mdsio_readfield.f, at line number 1651

when I try to pickup. It's in the read of AREA because I get 7 lines
of:

MDSREADFIELD: opening global file: pickup_seaice.0000026280

The problem doesn't seem to arise unless the pickups came from an MPI job.
There may be an issue in joinpickup. I get:

Offset outside string at
/home/twnh/models/MITgcm_c40pre9/utils/scripts/joinmds line 299.

when I try joinpickup on the pickup_seaice tiles. It builds a single file, 
but it's just 95% of the size I expect.

Thanks, Tom.
P.S. I got a slowdown of just 22% with the ice. This doesn't seem too bad
to me.


On Wed, 12 Feb 2003, Dimitris Menemenlis wrote:

> 
> >> It now seems to work fine. I've integrated for several 10,000 steps
> >> without any problems. I'll look in detail and let you know if I find any
> >> other issues. What did you fix?
> 
> Tom, thanks for all your help in the testing and debugging the sea-ice code.
> What I changed was the way in which option SEAICE_EXTERNAL_FLUXES is
> implemented.  Jinlun and I rely on internal, pkg/seaice, bulk formulae to
> compute fluxes over the complete integration domain, whether there is sea-ice
> or not.  Option SEAICE_EXTERNAL_FLUXES allows one to mix and match pkg/exf
> bulk formulae over open ocean and pkg/seaice fluxes where there is sea-ice.
> The first thing that pkg/seaice does is to compute open ocean fluxes.  Then it
> goes ahead and modifies these fluxes where there is sea-ice.  In previous
> implementation of SEAICE_EXTERNAL_FLUXES, I replaced the results of pkg/seaice
> open-ocean, bulk-formulae fluxes with those computed by pkg/exf.  This seems
> to work fine for heat and salt fluxes (and also for wind stress in my small
> test domain).  But in your configuration you found that the wind stress
> computed by pkg/exf is incompatible with the sea-ice code, especially near the
> edges where there are issues of interpolating from C to B and back to C grid.
> I don't fully understand what caused your configuration to blow up.  But a
> quick fix is to let pkg/seaice use its own internal estimates of wind stress
> for its computations, and then to replace wind stress with that produced by
> pkg/exf at all grid locations where there is no sea-ice.
> 
> Dimitris
> 
> -- 
> Dimitris Menemenlis                      menemenlis at jpl.nasa.gov
> Jet Propulsion Lab, MS 300-323           tel: 818-354-1656
> 4800 Oak Grove Dr, Pasadena CA 91109     fax: 818-393-6720
>