Re: trajectories crossing prime meridian

From: David Brown <dbrown_at_nyahnyahspammersnyahnyah>
Date: Thu Oct 04 2012 - 11:33:30 MDT

Hi Cathy,
It is true that our code could probably be improved to handle crossing the cyclic longitudinal boundary with less user intervention. If you can send us code illustrating your use case, it would be helpful. Thanks,
 -dave

On Oct 4, 2012, at 10:14 AM, Adam Phillips wrote:

> Hi Cathy,
> I don't have any experience drawing trajectories, but I think you are
> right about the 360->1 issue. I know you said you don't want to alter
> your longitudes, and understandably so, but just to figure out what is
> going on can you do a where statement to alter the longitudes within the
> script to see if that fixes things?
> lon = where(lon.eq.360,0,lon)
>
> Let us know how that turns out. Perhaps someone else might have a
> different/better suggestion...
> Adam
>
> On 10/03/2012 09:03 AM, Cathy Smith wrote:
>> NCL users
>> I am trying to plot trajectory paths using gsn_polyline on a polar
>> stereographic projection ( gsn_csm_map_polar). The paths plot nicely
>> except where they cross the prime meridian where they then plot a whole
>> latitude circle before finishing correctly. I looked up the issue in the
>> mailing list and saw that one should have pres@mpGreatCircleLinesOn=True
>> in the code. I tried that and it didn't appear to do anything. (I have a
>> sample image available if that isn't clear).
>>
>> I know the longitudes switch from 360 to 1 for the errant trajectories
>> and I assume that is the issue. I'd like to avoid trying to change the
>> longitudes as I would like the code to work for any trajectory and the
>> code logic might be complicated. Is there an way to do this w/o changing
>> longitudes?
>>
>> (I am using NCL v 6.0.0 on redhat linux.)
>>
>> Thanks for any advice.
>>
>> Cathy Smith
>>
>
> --
> ______________________________________________________________
> Adam Phillips asphilli@ucar.edu
> NCAR/Climate and Global Dynamics Division (303) 497-1726
> P.O. Box 3000
> Boulder, CO 80307-3000 http://www.cgd.ucar.edu/cas/asphilli
>
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Received on Thu Oct 4 11:33:41 2012

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