[GEMPAK #RVY-668229]: Meteogram y axis query

> Hello,
> We're plotting meteograms, for example with metar data from station
> PLCH, and see
> that one or more traces are located at the bottom of the segment of the
> y axis. For example,
> the attached .gif image shows what we get with TRACE1=skyk. (I've not
> found anything
> in the support archives about this.) We tried some combinations of the
> range parameters,
> but had no  idea what we were doing, not knowing what value of y might
> be assigned to
> the station model. Suggestions or comments will be welcomed. Thanks,
> John M.
> 
> 

John,

The behavior of character and symbol plotting is described in the SFGRAM
help under the section:

    Up to four parameters may be plotted along each axis.  The 
    parameters must be separated using semicolons.  Character
    and symbols may only be plotted in positions 1, 2 or 3,
    where position 1 is at the bottom of the trace, position 2
    is in the middle and position 3 is at the top.

This means that each trace, in addition to having y axis ranges associated with 
the left
and right sides (separated by the "!" character), is separated into thirds. The
plotting of sky coverage and wind barbs may therefore be plotted in the
bottom third of the trace, the middle third, or the top third. Some symbols
such as the wind barks do best in the middle third so they don't get clipped.

If your TRACE1 had for instance:
TRACE1 = relh;skyk;wsym!clds

You would have cloud coverage in the bottom third, because it is in the 1st 
position 
of the right hand parameter list (that is, you have the option of placing the 
symbol/text parameters in either the left or right parameter group), sky/wind 
symbol in the
middle third, and weather symbols in the upper third.

The ability to place symbol/text parameters on either side of the "!" character
gives you the flexibility to combine parameters that have common axis ranges
while still having symbols in proper locations.

You'll note in the tutorial example:
http://www.unidata.ucar.edu/software/gempak/tutorial/answers/graphing_answer1.html

which uses: 
TRACE1 = skyc:1:2;brbk:1:2/5;6!;;wsym:1:2;tmpc:1:2/;;11;3

The right hand side of the "!" has parameter WSYM placed into position 3
so as not to overlap positions 1 and 2 which are used on the left side.
Skipped positions in the list maintain correct position location.

Now, the archives should show something about this topic!

Enjoy,

Steve Chiswell
Unidata User Support



Ticket Details
===================
Ticket ID: RVY-668229
Department: Support GEMPAK
Priority: Normal
Status: Closed