[ferret_users] contour/fill and contour/line - different algorithm?

[Paul Young <Paul.J.Young@xxxxxxxx>]

Hi all,

I've been doing some plots where I do a "fill" with a "contour/line"  
over the top. This has worked out fine for the most part, but today  
I've been trying it on some data where I transform the pressure axis  
to log pressure. In essence, the problem is that the contour lines do  
not line up with the shading, mostly at higher altitudes. (see  
attached) The vertical model levels are certainly more spread out  
there, but I would have guessed that the contour/line would still  
follow contour/fill.....
Commands follow:

use my_water_vap_climatology.nc 							!Model water vapor output

define axis/depth/from_data/name=lnpz/z ln(z[gz=my_data])	!Put on log  
pressure axis
let x_lnp = my_data[gz=lnpz@asn]

let zmin = 250											!Set up plot (range and axes etc)
let zmax = 25
ppl axlabp -1, 0
ppl tics 0.125, 0.25, 0, 0

set region/z=`ln(zmin)`:`ln(zmax)`
fill/lev=($my_levels)/nokey \
  (x_lnp[l=@max]-x_lnp[l=@min]) 						 	!Contour/fill yearly range
contour/over/nolab/lev=($lv) \
  (x_lnp[l=@max]-x_lnp[l=@min])							!Over plot contour lines -  
PROBLEM HERE?!
Thanks for any pointers,

Paul