[ncl-talk] how to change tickmark to standard pressure levels in WRF cross-section plot

[music piano]

Hi, Everyone

Example is here
http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/CROSS_SECTION/wrf_CrossSection3.htm

The tickmarks here are 1010, 960, 910...... But I want standard levels such
as 1000, 950, 900.....

My analysis of the code is as follow:
(1)
rh_plane = wrf_user_intrp3d(rh,p,"v",plane,0.,opts)

It interpolates the data into pressure coordinate. However, the pressure
levels are not standard levels as I check the subroutine "WRFUserARW.ncl" .
It begins with the highest pressure from the bottom, not from 1000. Thus,
the tickmark position represents nonstandard pressure

(2) opts_xy at tmYLMode = "Explicit"
opts_xy at tmYLValues = fspan(0,zspan,nz) opts_xy at tmYLLabels =
sprintf("%.0f",fspan(zmin,zmax,nz))

give labels to each tickmark position. Since the tickmark position is not
in standard pressure, it shows 1010, 960.....
I have tried to use @ tmYLMode ="Manual"  *tmYLTickStartF
<https://www.ncl.ucar.edu/Document/Graphics/Resources/tm.shtml#tmYLTickStartF>
*,
or set trXMaxF , none of them works. They still plot tickmark position.

I can possibly modify "WRFUserARW.ncl to let it interpolation to standard
levels, but that may require reinstalling NCL in the machine, which is hard.

Does anyone know how to produce tickmarks which specify the standard
pressure value?

Thank you very much
Richard
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