Re: 20010319: gempak units/contours

Will,

I look at your equation when I get a chance.

You might try using gdlist or gdmap to look at the data values
being computed in the region where you don't see contours.

Steve Chiswell
Unidata User Support

On Tue, 20 Mar 2001, W Hession wrote:

> 
> Steve,
>       Thanks for replying.  So are you saying that even though gempak
> displays omega as mb/s, it converts omega to Pa/s in a calculation as it
> does for mixing ratio?  Here is what I'm using
> 
> gfunc=quo(mul(-14.66,lap(mul(lav(omeg),add(10,stab)))),corl)
> 
> The constant is originally -146.6 but changed when changing mb/s >> Pa/s
> and K/km >> K/m.  Is the pressure conversion necessary?
> 
> 
> Also, concerning uncontoured regions with advection of MIXR.  these seem
> to occur in areas of minimum values of MIXR.  even if no value is chosen
> for CINT.  Any suggestions.
> 
> Thanks, Will
> 
> 
>  On Mon, 19 Mar 2001, Steve Chiswell wrote:
> 
> >
> > James,
> > I was not able to view your attatched gif.
> >
> > Some reasons why a contour plot would have regions uncontoured:
> > 1) you have requested more than the maximum number of contour levels
> > 2) There is missing data values (-9999.) for at least one of the
> >    parameters used in the computation at those grid points (or
> >    check for "negative" mixing ratio or relh values at those points).
> >
> > When dealing with computations, the most significatnt is mixing ratio
> > is used in non-dimaensional units (eg g/g rather than g/kg as you normally
> > use in output- eg there is a 10^3 term here). Omega computations are 
> > generally
> > carried out in SI units of Pa S-1 (10^2 magnitude here).I'd have to see what
> > your omega calculation is involving, but you will want to make sure that
> > terms of equations are properly handled in units. If you can let me know
> > what the calculation is that you are seeing scaled 10^1 too high, I can
> > take a look.
> >
> > Steve Chiswell
> > Unidata User Support
> >
> 
>