[ncl-talk] polar plot and gsnAddCyclic

[Marston Johnston]

Hi Adam,

 

Thanks for the clarification. Makes sense and this is one to save in memory for next time.

 

Best,

/M

 

From: Adam Phillips <asphilli at ucar.edu>
Date: Wednesday, 14 December 2016 at 23:10
To: Marston Johnston <shejo284 at gmail.com>
Cc: "ncl-talk at ucar.edu" <ncl-talk at ucar.edu>
Subject: Re: [ncl-talk] polar plot and gsnAddCyclic

 

Hi Marston,

Thanks for providing your data file and a easy to run script as that always makes debugging so much easier. 

 

Looking at your longitudes they are regularly spaced from 1.267E to 357.349E by 2.5254 degrees. I believe the gsn_add_cyclic error message is coming in because the spacing between your first and last longitudes is much larger than the spacing between all other neighboring longitudes: 3.91 degrees. Thus, you can set gsnAddCyclic = True (=the default) and NCL will interpolate between the first and last longitudes when plotting, but it will warn you that it isn't sure it should be doing this.

 

Thus, if you are fine with NCL interpolating over the larger distance over the prime meridian I do not think you need to worry about the error messages. If you really want to get rid of them you can try interpolating to a new longitude between your first and last longitudes (that will result in very irregular longitude spacing and still might not get rid of the error messages) or interpolating to a new grid (say a 2.5 degree grid that starts at 0).

 

Hope that helps!

Adam   

 

On Wed, Dec 14, 2016 at 12:25 PM, Marston Johnston <shejo284 at gmail.com> wrote:

Hi Dennis,

 

Appreciate you looking into this.

My script: plot_tr_stats.ncl

Data: stat_trs_scl_VOR850_neg_1.nc

 

The files are uploaded.

 

Best,

/M

 

 

From: <ncl-talk-bounces at ucar.edu> on behalf of Dennis Shea <shea at ucar.edu>
Date: Wednesday, 14 December 2016 at 18:21
To: Marston Johnston <marston.johnston at gu.se>
Cc: "ncl-talk at ucar.edu" <ncl-talk at ucar.edu>
Subject: Re: [ncl-talk] polar plot and gsnAddCyclic

 

I think you will have to provide a clean script and the data for ncl-talk to address this issue.

ftp ftp.cgd.ucar.edu

anonymous

your_email

cd incoming

put ... script ...

put ... data ...

quit

Let ncl-talk know after successful completion of the ftp transfer.

THX

 

On Mon, Dec 12, 2016 at 5:32 AM, Marston Johnston <marston.johnston at gu.se> wrote:

Hi,

 

I’m trying to make some plot using the polar stereographic projection.

When I set res at gsnAddCyclic = False, everything works well but the plots have a gap at 0 deg longitude. However, whenever I set this to True, I get the standard warning that my longitude data doesn’t go to 360, but I don’t get a gap in the data. 
Is there a way to remove the gap and the warning? I was thinking of just extending the longitude copying the last longitude values to this new line, but searching for something more elegant. 
Note: this doesn’t happen when using Mercator projection.

 

/M

 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Marston S. Johnston, PhD

Department of Earth Sciences

University of Gothenburg, Sweden

Email: marston.johnston at gu.se

SkypeID: marston.johnston 

Phone: +46-31-7864901 

Only the fruitful thing is true!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 


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-- 

Adam Phillips 

Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR

www.cgd.ucar.edu/staff/asphilli/   303-497-1726 

 

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