[MITgcm-devel] ptracers extension (new thread following "status")

[Jean-Michel Campin]

Hi,

I thought it would be more clear to start a new thread, since
this one ("Status") is still going on with pkg/seaice discussion.

I support Dimitris' plan, because right now ptracers only 
handle 3-D tracers which are advected by uVel,vVel,wVel.
To have an extension to seaice tracer require a new set of
arrays + S/R  and it's not completely clear how general
it should be (we may want to enable a 2-D passive tracer
to be advected with "surface current", also with cheapAML winds, 
or with thsice related variables, but this requires some options
regarding the flow field to use and which mask/volume to use).

The advection S/R (pkg/generic) can be used for any tracer /
flow field (or at least, can/should be changed if it's not fully 
the case), and it's already a good point. 

And it makes sense for me to have a 1rst try within pkg/seaice first,
then to see how general this 2-D passive tracer case is (flow field,
mask/volume) and then to move it to pkg/ptracers when things are 
more clear regarding extension to other 2-D passive-tracer cases.

Cheers,
Jean-Michel

On Thu, Feb 24, 2011 at 10:29:06AM -0500, Chris Hill wrote:
> Hi All,
> 
>  For what its worth, I think we should be getting this stuff going
> within a ptracers framework.
>  It would be a shame not to do that.
> 
> Chris
> 
> On Thu, Feb 24, 2011 at 9:42 AM, Menemenlis, Dimitris (3248)
> <Dimitris.Menemenlis at jpl.nasa.gov> wrote:
> > Gael, thank you for message. I know that your two scenarios were the starting point of discussions for ice age tracer but I don't yet know what Pierre decided to implement as I did not take part in discussions about this yesterday.
> >
> > Could you remind me what "extensive" and "intensive" mean. Do they mean area-based as opposed to volume-based? Eventually we should implement both. The first is more directly observable while the second seems to be a more meaningful measure of age.
> >
> > A third useful age diagnostic, down the road, will be to use several simultaneous age tracers that categorize fraction of first year ice, second year ice, etc., in each cell.
> >
> > The eventual hope is that we will be able to use one or more of the age diagnostics to better parameterize sea ice properties like drag, thickness distribution, and ice strength.
> >
> > Dimitris Menemenlis
> > 818-625-6498
> >
> > On Feb 24, 2011, at 1:01 AM, "Gael Forget" <gforget at MIT.EDU> wrote:
> >
> >> Hi Dimitris and Patrick,
> >>
> >> a few thoughts regarding ice tracers (salinity and age for now).
> >>
> >> My recollection is that there are currently two issues regarding the age tracer:
> >> (1) it is advected as extensive, whereas it is otherwise treated as intensive.
> >> (2) the lack of detail regarding the effect of individual growth/melt terms on age.
> >>
> >> With regard to generic ice tracers a choice will have to be made between
> >> extensive (as in SEAICE_SALINITY) and intensive (as in SEAICE_AGE).
> >> I wrote down the two scenarios equations for Pierre so he knows how to
> >> proceed either way for the age tracer. I dont have a strong preference but
> >> 'intensive' would imply  a division by HEFF during advection (as opposed
> >> to diagnostics) that could prove problematic. So I am wondering whether
> >> it would it be good time to switch SEAICE_AGE to extensive.
> >>
> >> Cheers,
> >> Gael
> >
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> 
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