[ncl-talk] A question about vertical section of wind vector with wrfout data

[Mary Haley]

OOPS! After I looked more carefully at the second plot, I realized it is
not correct because I forgot to remove the tfDoNDCOverlay resource.

This resource should not be set if you are setting the sfX/YArray and
vfX/YArray resources.

Please see the attached (hopefully fixed) script and new images (only the
second image is different).



On Fri, Sep 22, 2017 at 3:22 PM, Mary Haley <haley at ucar.edu> wrote:

> Dear Yan,
>
> I'm not an expert in this area, but I didn't see any responses to your
> question so I'll try to help.
>
> First, if I understand your question, I'm not sure how that particular
> figure was generated. I doubt it was done using wrf_vector, because is
> mainly for drawing surface vector plots. Also, if this is a plot of
> curvilinear data, then I doubt gsn_csm_vector_pres_hgt was used, because
> this assumes that the level dimension is a coordinate array attached to the
> data.
>
> It's a bit tricky to do vertical cross sections with vector data on a
> curvilinear grid because then what do your X and Y axes actually
> represent?  Since the x,y value at each grid location is different, you
> can't really put meaningful labels on the X and Y axis.
>
> What exactly do you want to take the cross section of? You can arbitrarily
> slice the data across some index value in the latitude or longitude
> direction, but then again, the X and Y axis will not really have any
> meaning, and so we can only label them with index values.
>
> I created a simple script that reads QVAPOR, and U/V (at mass points) off
> a WRF file, and then creates vectors over a filled contour plot at an
> arbitrary latitude index value across all height/longitude values.
>
> I plotted the data two ways:
>
> The first way I let NCL label the X and Y axis with array index values.
>
> The second way I set trGridType to TriangularMesh, which allows us to have
> 2D X and Y axis values set.  Notice that this changes the shape of the plot
> and also the X and Y axis now have labels.
>
> As a side, I should point out that it's just the height values that are
> different at each location.  At any particular height location, the
> longitude values are actually all the same across a latitude index, and
> vice versa.  But, I think NCL doesn't like it when you try to plot data
> using a 2D array for one axis and a 1D array for the other axis, so I
> propagated the 1D longitude array to a 2D array using conform.
>
> I'm not sure this is what you want, but hopefully you will see that you
> need to be careful with cross sections of curvilinear data.
>
> --Mary
>
>
>
>
> On Thu, Sep 14, 2017 at 8:07 PM, 古枫玥瑟 <6544191 at qq.com> wrote:
>
>> Dear ncl-talk,
>> I want to draw a figure as shown below. Is the vertical section of wind
>> vector drawed by "gsn_csm_pres_hgt_vector" or  "wrf_vector"?
>> My data is WRF-ARW data like "wrfout_d03_2016-08-11_00:00:00".
>> May I follow with the example of  "*wrf_CrossSection4.ncl
>> <http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/CROSS_SECTION/wrf_CrossSection4.ncl> "or
>> "*h_lat_7.ncl <http://www.ncl.ucar.edu/Applications/Scripts/h_lat_7.ncl>*"
>> or "*vector_5.ncl
>> <http://www.ncl.ucar.edu/Applications/Scripts/vector_5.ncl>*" or any
>> other?*
>> *
>> <http://www2.mmm.ucar.edu/wrf/OnLineTutorial/Graphics/NCL/Examples/CROSS_SECTION/wrf_CrossSection4.ncl>*
>> Please give me some guidance.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Many thanks in advance
>>
>> Regards
>>
>> Yan
>>
>> Shanghai Institute of Meteorology,China.
>>
>>
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>>
>
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