Re: [ferret_users] sigma coordinate slice.

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi John,
The second argument of zaxreplace needs to be a variable on the source 
axis, defining the destination Z axis values as a function of the depths 
on the source Z axis. From my reading of what you are doing, it doesn't 
sound like that's what you have tried. You need to use this argument to 
define the depths associated with the vertical layers.

Please take another look at the Users Guide, and also the FAQ on sigma 
coordinates
http://www.ferret.noaa.gov/Ferret/FAQ/data_management/sigma_coordinate_demo.html. 
There is also a script sigma_coordinates_demo.jnl which runs the 
commands in the FAQ.

I have added a cross-reference to this FAQ from the description of 
ZAXREPLACE in the Users Guide to make it easier to find.

Ansley


John Luick wrote:

> I wish to plot a vertical slice of temperature. The following command 
> works:
> shade/l=500/k=1:18/y=100 temp
> ...but it plots on a sigma coordinate axis (from 0 down to -1).
> So, I try to get it to plot on a depth axis using:
> DEFINE AXIS/Z=0:2000:10/UNIT=meters/DEPTH zdepth
> LET temp1 = ZAXREPLACE(temp,h,z[gz=zdepth])
> shade/L=500/y=100/z=0:2000 temp1
> ...but this gives me an error message (illegal limits: Z limits of 
> data and depth fields must match).
> In my case, "h" is the bathymetry variable. I dont know the exact 
> maximum value of h, but it's over 2000.
>
> Can someone please point out the error of my ways? Oh yes, in case it 
> helps:
> yes? show axis zdepth
> name       axis              # pts   start                end
> ZDEPTH    DEPTH (m)          201 r-  0                    2000
>   Axis span (to cell edges) = 2010
>
> I'm not sure how to work out the corresponding limits of variable temp1.
>
> Thanks
>
> John