Re: [ferret_users] sigma coordinate slice.

[John Luick <john.luick@xxxxxxxxxx>]

Ansley,

thanks for your assistance on this - prompt as always, albeit
in this case you just repeated what was in the documentation,
and I had already tried in vain to decipher that mystic and
obtuse cabbalah before I wrote. In the end I followed the path
of F. Guillen, and found success - see my notes below.

Cheers 
John
p.s. to Francisco, if you see this: to quote R. Kipling,
"You're a better man than I am, Gunga Din."

!To get depth instead of sigma coordinates:
!(from Francisco Guillen, 
! ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_2003/msg00150.html
!/ROMS/roms-2.2/jll_ferret1.jnl
set win 2   !leaves s-coord window open and opens another
let bb= h + 0*temp[l=500]
let zz=(z+.03)*bb
def axis/z=0:-2910:1/depth z100
let znew = z[gz=z100]
let temp_depth = ZAXREPLACE(temp,zz,znew)
shade/L=500/y=100/vlimits=0:-1200:50 temp_depth


---- Original message ----
>Date: Wed, 09 Nov 2005 09:44:06 -0800
>From: Ansley Manke <ansley.b.manke@noaa.gov>  
>Subject: Re: [ferret_users] sigma coordinate slice.  
>To: John Luick <john.luick@jcu.edu.au>
>Cc: ferret_users@noaa.gov
>
>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
>>