[ncl-talk] can't seem to make my arrows bigger

Mon Apr 27 14:22:39 MDT 2015

Hi Kyle and other NCL-ers,
Thanks for the ideas.
I had already tried the default values and got tiny arrows.
I had already tried printing out the default values to see what they were so
I could tweak them.
Attached are the data, pared-down program, and resulting plot.
Let me know if I need to use the NCL ftp site.

Here's the output from this program:

(0) ref len is 0.0106101

(0) ref mag is 5.77226e+09

(0) ref dist is 0.03

I'm open to any and all suggestions.
I suspect I need to scale the Z values and/or do some kind of
pressure-weighting (my attempts at this so far haven't worked)
or there's something obvious I'm missing...
Thanks for any insights!
-Lesley

On Mon, Apr 27, 2015 at 10:12 AM, Kyle Griffin <ksgriffin2 at wisc.edu> wrote:

> Hi Lesley,
>
> First, please make sure ncl-talk is included in future replies, as others
> may also have useful insights.
>
> My next suggestion would be to try unsetting the vcRefMagnitudeF and
> vcRefLenghtF - NCL has the ability to calculate these by default to create
> a plot that at least looks somewhat reasonable. Although the resultant plot
> is not likely to be the results you actually want, you can look at the
> settings it chooses and use that as guidance.
>
> Some code like this after the plot is drawn might be insightful:
>
> getvalues plot   ; plot is whatever you have saved your vector plot as,
> e.g. plot=gsn_csm_vector(....)
>   vcRefMagnitueF : calc_ref_mag
>   vcRefLengthF : calc_ref_length
> end getvalues
>
> print("Mag: "+calc_ref_mag+"   Length: "+calc_ref_length)
>
>
> If this doesn't provide the insight you are looking for, please include
> your code (even if simplified) and data in a response if you can, using the
> NCL FTP site if necessary, and someone can take a look at it. I'm also
> wondering if there might be some internal limits to vector size settings,
> but at the moment, I can't think of any good reason why this would be the
> case (but I'm also not a developer, either).
>
>
> Kyle
>
> ----------------------------------------
> Kyle S. Griffin
> Department of Atmospheric and Oceanic Sciences
> University of Wisconsin - Madison
> Room 1421
> 1225 W Dayton St, Madison, WI 53706
> Email: ksgriffin2 at wisc.edu
>
> On Mon, Apr 27, 2015 at 10:38 AM, Lesley Smith - NOAA Affiliate <
> lesley.l.smith at noaa.gov> wrote:
>
>> Hi Kyle,
>> I appreciate you writing me back.
>> I'm plotting meridional and vertical EP flux with my arrows, not winds.
>> The values are of magnitude 1.e10 and 1.e8
>> For example, meridional_EP_flux: min=-1.6812e+10   max=1.07296e+10
>>
>> vertical_EP_flux: min=-1.53672e+08   max=1.33486e+08
>>
>> Thus, my values *are* on the order of  2,000,000,000
>>
>>
>> Your suggestions result in:
>>
>> fatal:VectorPlotDraw: VVECTR - VECTOR NDC LENGTH TOO GREAT
>>
>> fatal:VectorPlotDraw: error drawing vectors
>>
>> fatal:VectorPlotDraw: draw error
>>
>> fatal:PlotManagerDraw: error in plot draw
>>
>> fatal:_NhlPlotManagerDraw: Draw error
>>
>> Do you have any other suggestions?
>> Thanks,
>> -Lesley
>>
>> On Fri, Apr 24, 2015 at 7:40 PM, Kyle Griffin <ksgriffin2 at wisc.edu>
>> wrote:
>>
>>> Hi Lesley,
>>>
>>> I think you've switched your reference vector settings around. You
>>> should be either making vcRefMagnitudeF *smaller* or making vcRefLengthF
>>> *larger*. These act in concert to control the size of the vectors in your
>>> plot. Each actually controls the magnitude and length of the vector in the
>>> reference vector box in the bottom right of your attached image. You'll
>>> note that in this current setting, you would need a wind speed of
>>> 2,000,000,000 m/s to have a vector plotted at that size. In reality, you
>>> might want to set vcRefMagnitudeF to a value somewhere between 10.0 and
>>> 50.0. If this still doesn't make your vectors large enough, reduce the
>>> vcRefMagnitudeF to 1.0 and I'm sure you'll see some EP flux arrows appear.
>>> You can always check the max() and min() of your vector field if you aren't
>>> sure the actual magnitudes you are dealing with.
>>>
>>> Let us know if you have any more questions.
>>>
>>>
>>> Kyle
>>>
>>> ----------------------------------------
>>> Kyle S. Griffin
>>> Department of Atmospheric and Oceanic Sciences
>>> University of Wisconsin - Madison
>>> Room 1421
>>> 1225 W Dayton St, Madison, WI 53706
>>> Email: ksgriffin2 at wisc.edu
>>>
>>> On Fri, Apr 24, 2015 at 4:20 PM, Lesley Smith - NOAA Affiliate <
>>> lesley.l.smith at noaa.gov> wrote:
>>>
>>>> Hi gang,
>>>> I'm using gsn_csm_pres_hgt_vector to make a plot.
>>>> In the past it has worked great for me.
>>>>
>>>> This time, I can't seem to make my arrows big enough to see
>>>> anything.  I attach a plot of contoured EP Divergence with the
>>>> corresponding 2 EP components in vector form overlaid. The components
>>>> are many orders of magnitude greater than the divergence.
>>>> I've tried changing vcRefMagnitudeF and vcRefMagnitudeF to
>>>> a variety of values and the arrows look the same.
>>>> I tried scaling the vertical component (like one of the examples on the
>>>> NCL website) to no effect.
>>>>
>>>> Eventually when I make vcRefMagnitudeF too small it suddenly gives the
>>>> error:
>>>>
>>>> fatal:VectorPlotDraw: VVECTR - VECTOR NDC LENGTH TOO GREAT
>>>>
>>>> fatal:VectorPlotDraw: error drawing vectors
>>>>
>>>> fatal:VectorPlotDraw: draw error
>>>>
>>>> fatal:PlotManagerDraw: error in plot draw
>>>>
>>>> fatal:_NhlPlotManagerDraw: Draw error
>>>>
>>>>
>>>>
>>>> I'd love any suggestions!
>>>>
>>>> Thanks!
>>>>
>>>> -Lesley
>>>>
>>>> _______________________________________________
>>>> ncl-talk mailing list
>>>> List instructions, subscriber options, unsubscribe:
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>>>>
>>>>
>>>
>>
>
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