[Support #ZDT-182699]: PV in IDV

Hi Jim-

I have a met question for you.  If I negate the grid for the GFS, I get what I 
would consider as correct results.  However, for the NAM, the values are then 
wrong.

If you download the nightly build and run the Displays->Favorite 
Bundles->NAM211->Isentropic Potential Vorticity bundle, you should get a 
reasonable depiction.  Can you confirm this?

However, if you do a GFS isosurface, the values are negated.  If you set the 
isosurface value to -2, it should look like the NAM 2 IPVunit surface.   The 
GEMPAK formula is:

-GRAVTY*AVOR(V)*dTheta/dP

There was a note in the code that using the - gives the wrong values, but I'm 
stumped as to way it works with one grid and not the other. Both are GRIB1, 
both have a vertical dimension of P in hectopascals.  Any thoughts on this?

I'll keep looking into it, but thought I'd turn to a professional for some 
advice.

In the meantime, you can just use the -2 isosurface for the GFS. ;-)

Don

> > I was trying to plot an isosurface.  That "works", but the result is
> > best described as "gobbledygook."  The ability to do a 2 PVU isosurface
> > is really powerful for teaching PV thinking.  That's when I noticed the
> > error.
> 
> I found one error which was that absolute vorticity was being calculated 
> incorrectly.  That will be fixed in the nightly build.  However, I'm now 
> trying to get IPV correct. I compared the results from GEMPAK and they match.
> 
> However, IPV is even worse now. :-( I'll have to do some plan view plots in 
> GEMPAK to compare with since I don't have any other program to show what the 
> isosurface should look like.
> 
> Thanks for your patience.
> 
> Don
> 
> > Unidata IDV Support wrote:
> > > Hi Jim-
> > >
> > > I've moved this to the support system.  Best to send questions to 
> > > support-idv instead of me directly so we can better track these issues.
> > >
> > > Thanks for catching this. Did this ever work?  I've always done this as a 
> > > volume since IPV needs several levels. If you select 2 (or more) levels 
> > > in the levels panel, you'll be able to do the slice for a plan view.  
> > > However, the list of levels in the control will not reflect the levels 
> > > you selected, but the entire list of levels.  We're working on a fix to 
> > > this.
> > >
> > > Don
> > >
> > >
> > >> ERROR: Creating display: Contour Plan View
> > >> org.python.core.PyException
> > >> Traceback (innermost last):
> > >> File "<string>", line 1, in ?
> > >> at visad.FlatField.derivative(FlatField.java:4044)
> > >> at visad.FlatField.derivative(FlatField.java:4485)
> > >> at
> > >> ucar.unidata.data.grid.DerivedGridFactory.partial(DerivedGridFactory.java:2366)
> > >> at
> > >> ucar.unidata.data.grid.DerivedGridFactory.createIPV(DerivedGridFactory.java:1954)
> > >> at
> > >> ucar.unidata.data.grid.DerivedGridFactory.createIPV(DerivedGridFactory.java:1880)
> > >> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> > >> at
> > >> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> > >> at
> > >> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> > >> at java.lang.reflect.Method.invoke(Method.java:597)
> > >>
> > >> visad.VisADException: visad.VisADException: derivative: d_partial_s not
> > >> in domain or reference
> > >> ERROR: Creating display: Contour Plan View
> > >> org.python.core.PyException
> > >> Traceback (innermost last):
> > >> File "<string>", line 1, in ?
> > >> at visad.FlatField.derivative(FlatField.java:4044)
> > >> at visad.FlatField.derivative(FlatField.java:4485)
> > >> at
> > >> ucar.unidata.data.grid.DerivedGridFactory.partial(DerivedGridFactory.java:2366)
> > >> at
> > >> ucar.unidata.data.grid.DerivedGridFactory.createIPV(DerivedGridFactory.java:1954)
> > >> at
> > >> ucar.unidata.data.grid.DerivedGridFactory.createIPV(DerivedGridFactory.java:1880)
> > >> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> > >> at
> > >> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> > >> at
> > >> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> > >> at java.lang.reflect.Method.invoke(Method.java:597)
> > >>
> > >> visad.VisADException: visad.VisADException: derivative: d_partial_s not
> > >> in domain or reference
> > >>
> > >>
> > >>
> > >
> > >
> > > Ticket Details
> > > ===================
> > > Ticket ID: ZDT-182699
> > > Department: Support IDV
> > > Priority: Normal
> > > Status: Open
> > >
> > >
> >
> >
> 


Ticket Details
===================
Ticket ID: ZDT-182699
Department: Support IDV
Priority: Normal
Status: Open