Re: [ferret_users] how to get Pressure(mb) axis data in reverse order

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

Hi -
The values in the list that you use to define an axis need to be 
increasing, and then the /DEPTH qualifier tells Ferret whether a plot of 
them should increase (as in an atmospheric dataset) or decrease as in an 
oceanographic dataset.  If  the data in  your file q.nc is reversed with 
respect to the axis you want to define, you can read it in with the 
/ORDER=-z  qualifer and then define the new axis with /DEPTH and regrid 
to it with @ASN regridding.


! Compare what the plots look like, before doing any regridding:
  set data q.nc; fill q[l=1,x=-170] ; cancel data q.nc
  set data/order=-z q.nc; fill q[l=1,x=-170] ; cancel data q.nc

 set data/order=-z q.nc
 let press = {0.0, 7.76, ...}
 def axis/depth/z/units=mb zpressure = press
  let q2=q[gz=zpressure@ASN]
 
Yogesh K. Tiwari wrote:

> Hello Ferret Users,
>
> I want to change sigma level z-axis with pressure(mb) values so I 
> wrote a script.
>
> !++++++++++++++++++++
>
> set data q.nc
>
> let press =\
>   {0.0,7.76486715808502,19.1474920954818,\
> 5.5095334329671,57.7252298204432,86.0958233667092,\
> 120.320114961464,159.597308168984,205.375139312848,\
> 269.693181583253,363.907443320277,480.335709752363,\
> 600.936070971621,710.819107916518,802.135476614033,\
> 872.668797870758,923.727954421369,958.711821388422,\
> 982.300930711410,999.956798673119}
>
> define axis/z/units=mb zpressure=press
>
> let q2=q[gz=zpressure@ASN]
>
> fill m2[l=1,x=-170]
> !++++++++++++++++++++++
>
> The defined 'press' values are monotonic increasing order. Monotonic 
> decreasing order definition not working.
>
> Here the fill plot which I get has the y-axis in reverse order, means, 
> 0 in lower and 1000 mb in upper part of axis range.
>
> I tried to change the order of defined pressure values 'press', I kept 
> it in monotonic decreasing order but ferret complains .....**NOT A 
> monotonic order.
>
> I tried to keep 'DEPTH' qualifier but problem did not solved and tried 
> 'vlimits' to reverse it but the whole map reverses with the reversing  
> y-axis pressure values.
>
> Can any body help, how to reverse only the pressure values on y-axis, 
> or if any thing wrong in my script.
>
> Many thanks for your help.
>
> Regards,
> Yogesh