[ferret_users] vertical coordinates

[Brockmann Patrick <Patrick.Brockmann@xxxxxx>]

Hi all,

How to store two vertical coordinates in different order in a netCDF file ?

I have a 3D variable XYZ where Z is a sigma vertical coordinate
(from 1 at ground to 0 at the top of the atmosphere).
The netcdf variable is stored with k=1 ground, k=11 top of the atm

Now, if I define sigma as
sigma = 0.989417, 0.9596861, 0.9065547, 0.8214576, 0.7043947, 0.5639313,
   0.4149028, 0.2744395, 0.1573766, 0.07227948, 0.01914804 ;
So with a decreasing order
when I open the file with ferret, the axis is reordered and variable is 
then available with
an increase axis.
Thus I get
yes? shade var[k=1] 
representing top of the atmosphere. It should be ground.

The problem could be a simple convention to accept but it is more 
complicated to explain
if you have 2 vertical axis such as an altitude (with an increasing 
order) and a sigma (with a descreasing order).
In first case k=1 will represent ground, k=11 in the second case.
k=1 should reprensent the ground in both case.

So is there a way to store in a netcdf file, one vertical axis in a 
descreasing order and one in
an increasing order ?

Patrick