[ncl-talk] 2ND TIME POST: add polyline with gsn_csm_pres_hgt_vector

[Zhifeng Yang]

Hi Dennis,
Yes, you are right Height is just added as the label for right-Y axis, not
like gsn_csm_xy2.ncl. I searched "gsn_csm_pres_hgt_vector" the code (
gsn_csm.ncl). However, I did not find how it calculates the height using
pressure value. Do you know who wrote this code (gsn_csm.ncl) or do you
know who is more familiar with this code? Thank you,

Zhifeng

On Thu, Aug 20, 2015 at 10:31 AM, Dennis Shea <shea at ucar.edu> wrote:

> " I am not sure how to add a polyline using the right y-axis"
>
> I did not write this so I am guessing:
>
> I think the right-y-axis ("Height") is not a y-coordinate. Rather,
> 'under-the-hood,' a function (say) Height = f(pressure) was used to
> estimate the heights for labeling purposes.
>
> if the x-axis is (say, lat or lon), and you have:
>       polyline_values = f(x,height)
> then you may have to recast the 2nd line in terms of pressure and add
> like the 1st polyline
>
>
>
>
>
> On Wed, Aug 19, 2015 at 2:16 PM, Zhifeng Yang <yangzf01 at gmail.com> wrote:
> > Hi
> >
> > Sorry for posting this problem again. Since I haven't received reply
> from my
> > previous post, I promote it by myself.
> >
> > I want to add a polyline on a image generated by gsn_csm_pres_hgt_vector,
> > and the y value of the polyline is height, which is the right y-axis. I
> can
> > add a polyline using the left y-axis, but I need to reverse pressure to
> plot
> > a polyline. I don't know how to plot a polyline with reversed y-axis.
> Most
> > important, I am not sure how to add a polyline using the right y-axis. Do
> > you know how to fix it?
> > Thank you.
> >
> > Best,
> > Zhifeng
> >
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