# [ncl-talk] Cross section vertical coordinate and tick mark labeling

Ryan Connelly rconne01 at gmail.com
Mon May 9 12:12:35 MDT 2016

```Hi Evelyn,

Ryan

On Mon, May 9, 2016 at 11:28 AM, Evelyn Grell - NOAA Affiliate <
evelyn.grell at noaa.gov> wrote:

> Ryan,
>
> Your dbz array has been vertically interpolated, using wrf_user_intrp3d.
> This routine has a hard-wired number of vertical levels set to 100.
>
> Since you want to plot from 0-10 km, you should follow the example for a
> limited vertical extent:
>
>  http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/CROSS_SECTION/wrf_CrossSection4.htm
> <http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/CROSS_SECTION/wrf_CrossSection4.htm>
> in which your height (z) is also vertically interpolated to these 100
> levels.  If you follow what happens to zz in the online example, I think
> you will get what you want.  I have extracted the required lines and added
>
>    ; get height info for labels
>       zmin = 0.
>       zmax = 10.                         ; We are only interested in the first 10km
>       nz   = floattoint(zmax/2 + 1)        ; nz = # of tick marks (you want 6)
>
>         ; Find the index where 10km is - only need to do this once
>
>
>           zz = wrf_user_intrp3d(z,z,"v",plane,angle,opts)    ; interpolate z -> zz
>           b = ind(zz(:,0) .gt. zmax*1000. )                  ; get 1st index above zmax
>           zspan = b(0) - 1                                         ; level index to use
>
>              delete(zz)
>
>           delete(b)
>
> .....
>
>          opts_xy at tmYLValues      = fspan(0,zspan,nz)         ; Create tick marks
>
>         opts_xy at tmYLLabels        = sprintf("%.1f",fspan(zmin,zmax,nz))  ; Create labels
>
> Then when you actually do the plotting, you must set the max index to limit the vertical dimension:
>
>         contour_dbz = wrf_contour(a,wks,dbz_plane(0:zspan,:),opts_xy)
>
> Good luck,
>
> Evelyn
>
>
>
> On Sun, May 8, 2016 at 8:22 PM, Ryan Connelly <rconne01 at gmail.com> wrote:
>
>> Hi,
>>
>> I produce a vertical plane of, in this case, simulated reflectivity.  I
>> want to then manually define the y axis (in this case z) to have tick marks
>> every 2 km from 0 to 10 km.  This is proving surprisingly difficult.
>>
>> This WRF run has 39 vertical levels, yet somehow a PrintVarSummary of the
>> newly-created plane (below) reveals that its vertical extent is "100".  100
>> whats?  Not 100 vertical levels, not 100 meters or 100 km, not 100 hPa...
>>
>> I figured out how to use the tmYLValues and tmYLLabels options in xy
>> plotting resources (also below) to define where to put tick marks and what
>> to label them, to get me the 2-4-6-8-10 that I want, *but my problem is:
>> how do I get them to match the actual vertical coordinate of the data
>> (meters or km)?*  Right now, I can put in any numbers I want and it'll
>> put them there, but the contours don't move, so the actual height of the
>> data is not changing, and remains unknown.
>>
>> Variable: dbz_plane
>> Type: float
>> Total Size: 60400 bytes
>>             15100 values
>> Number of Dimensions: 2
>> Dimensions and sizes:   [Vertical | 100] x [Horizontal | 151]
>> Coordinates:
>> Number Of Attributes: 4
>>   _FillValue :  9.96921e+36
>>   units :       dBZ
>>   description : Reflectivity
>>   Orientation : Cross-Section: (27,254) to (142,156)
>>
>> ****************************************************
>>
>>  ; Options for XY Plots
>>         opts_xy                         = res
>>         opts_xy at tiYAxisString           = "Height (km)"
>>         opts_xy at cnMissingValPerimOn     = True
>>         opts_xy at cnMissingValFillColor   = 0
>>         opts_xy at cnMissingValFillPattern = 11
>>         opts_xy at tmYLMode                = "Explicit"
>>         ;opts_xy at tmYLValues              = fspan(0,100,6)
>>      ; Create tick marks
>>         ;opts_xy at tmYLLabels              = fspan(0,10,6)  ; Create labels
>>         opts_xy at tiXAxisFontHeightF      = 0.020
>>         opts_xy at tiYAxisFontHeightF      = 0.020
>>         opts_xy at tmXBMajorLengthF        = 0.02
>>         opts_xy at tmYLMajorLengthF        = 0.02
>>         opts_xy at tmYLLabelFontHeightF    = 0.015
>>         opts_xy at PlotOrientation         = dbz_plane at Orientation
>>
>>
>> Thanks,
>> Ryan
>>
>> --
>> Ryan Connelly
>> M.S. Student in Atmospheric Sciences, Stony Brook University
>> B.S. in Meteorology with Minors in Mathematics and GIS, Valparaiso
>> University
>> rconne01 at gmail.com
>> ryan.connelly at stonybrook.edu
>>
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>>
>

--
Ryan Connelly
M.S. Student in Atmospheric Sciences, Stony Brook University
B.S. in Meteorology with Minors in Mathematics and GIS, Valparaiso
University
rconne01 at gmail.com
ryan.connelly at stonybrook.edu
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