[cam-users] Hemispheric asymmetries

[David Noone]

Hi Camille,

As well as the ocean heat flux (Q0), do you set the mixed layer depth to
be the same in both hemispheres (i.e., MLD, the other boundary field for
the SOM)? When you say you have the orbital parameters set to be
symmetric, is this the same as saying that you have it running for a
perpetual equinox? My first thought is that if this is not the case, and
you start up in September, the Antarctic will be seeing a summer while
the Arctic a winter over, for instance, the subsequent DJF. As such, the
ice might melt in the SH, while grow in the NH (or something like that)
which would be consistent with your results.

I can't imagine the diffusion is a problem, as it is set to be the same
globally.


Hope this helps,

Dave



On Wed, 24 Jul 2002, Camille Li wrote:

>
> Regarding the following message, which I just posted,
> I forgot to mention that I do not call the LSM at all
> in order to get rid of Antarctica.
>
> ---------- Forwarded message ----------
> Date: Wed, 24 Jul 2002 18:28:29 -0700 (PDT)
> From: Camille Li <camille@atmos.washington.edu>
> To: cam-users@ucar.edu
> Subject: Hemispheric asymmetries
>
>
> I am trying to set up the CCM3.6 with the SOM to run in a land-free
> configuration (ORO and SGH = zero everywhere), and the sea ice keeps
> disappearing in the Southern hemisphere.
>
> I've changed the orbital parameters and ozone datasets to be "symmetric"
> about the annual cycle (i.e., NH January looks like SH July etc.), I have
> a QO that is symmetric about the equator with no annual cycle, and my
> initial temperature (all levels and subsurface levels) and u and v (all
> levels) fields are symmetric about the equator.  Given all this, the
> difference in sea ice concentration between the two hemispheres is
> apparent within the first few months.
>
> I read in the documentation that diffusion coeffiecents are tuned to give
> realistic polar night jets, but cannot find where this is in the code.
> Is this my problem?  Is there anything else I haven't considered, or is
> there some other hemispheric asymmetry that is hardwired into the model?
>
> Thanks,
> Camille Li
>
>
>
>
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