Streamfunction/velocity potential: using fish with libbjt

[See Hai Ooi]

Dear Mr Arlindo,

     Yes, I meant the convenience fields, especially
"one" which is, to me, simple and brilliantly done.

     Thank you.

Ooi See Hai


--- Arlindo da Silva <dasilva at ALUM.MIT.EDU> wrote:

> On Wed, Apr 2, 2008 at 10:49 AM, See Hai Ooi
> <axl419 at yahoo.com> wrote:
>
> > Dear Mr Arlindo,
> >
> >     Thank you very much.  After modifying slightly
> > your latest script, it works beautifully.  Please
> see
> > the attached document.
> >
> >     Your grads-1.9.0-rc1.win32_superpack.exe has
> > already included the B.-J.'s functions.  I need
> not
> > run the script under gradsdods.
>
>
> You need "gradsdods" to get the latest GFS forecast
> from NOMAD, not to run
> the extensions.
>
>
> >  I notice that
> > auxiliary fields replace your original enlarging
> and
> > resetting x domain sections.  If possible, I would
> > greatly appreciate it if you could kindly provide
> me a
> > brief write-up on the derivation of auxiliary
> fields
> > and the advection functions to understand them
> better.
> >
>
> I am not sure what you are referring to as
> "auxiliary fields"; "one" and
> "cosphi" is what I meant, and these are simply
> convenience fields. The
> actual vorticity/divergence is computed by functions
> madvu/madvv which are
> fully documented here:
>
>           http://opengrads.org/doc/udxt/libbjt/
>
> These functions figure out what to do in the
> boundaries without the need for
> you to enlarge the domain. Look under "ADVECTION
> FUNCTIONS". The new version
> of fish() to be released soon will provide functions
> fish_psi(u,v) and
> fish_chi(u,v) which calls these "advection
> functions" internally.
>
>     Arlindo
>
> --
> Arlindo da Silva
> dasilva at alum.mit.edu
>


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