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Re: Latitude/longitude, contours, map_set, iMap? [message #43910 is a reply to message #43886]

Tue, 03 May 2005 20:05

Kenneth P. Bowman
Messages: 585
Registered: May 2000

Senior Member

In article <1115172826.358757.121050@z14g2000cwz.googlegroups.com>,
"jamiesmyth_uni@yahoo.ca" <jamiesmyth_uni@yahoo.ca> wrote:

> The first
> problem I have is that the longitude data goes from 0-360 degrees.

That should not be a problem with MAP_SET. There is no reason to change
the coordinates.

> map_set, /continents, /mercator, /isotropic

This could be a problem, however, as the Mercator projection maps the
poles to +/- infinity in the y-direction. You might want to try the
cylindrical equidistant projection instead.

> contour, transpose(data.pv[*,*,0]), data.xlon, data.xlat, /overplot,
> nlevels=12
>
> The first command brings up a dialog box for the 'gridding wizzard' but
> when I click ok, nothing happens. The second looks 'more-or-less' ok
> but there seems to be a gap at 0 degrees. The gap is rather apparent
> when I fill the contours... Do I need to re-grid or triangulate the
> data? Is there a quick way to do any of this?

You just need to copy data on the Greenwich meridian to the "other end"
of the data array to make it contiguous, e.g,

pdata = TRANSPOSE(REFORM(data.pv[*,*,0]))
CONTOUR, [pdata, pdata[0,*]], [data.lon, 359.99], data.lat

That should work with either MAP_SET or iMAP (but I have never used
iMAP).

> Any ideas and help would be much appreciated... I'm supposed to be
> putting these figures (along with some polar stereographic projections)
> into a talk for thursday! Reaching for brown-paper bag... taking
> deep-breaths...
>
> Thanks
> Jamie
>

I can never make MAP_GRID work right with cylindrical equidistant
projections, so send me an e-mail and I'll send you a routine that draws
gridlines correctly. (k-bowman_AT_tamu.edu ... replace the _AT_)

Ken Bowman

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[Message index]

		Re: Latitude/longitude, contours, map_set, iMap? By: wmconnolley on Fri, 06 May 2005 01:58
		Re: Latitude/longitude, contours, map_set, iMap? By: Chris[2] on Wed, 04 May 2005 14:55
		Re: Latitude/longitude, contours, map_set, iMap? By: Ken Mankoff on Wed, 04 May 2005 12:51
		Re: Latitude/longitude, contours, map_set, iMap? By: jamiesmyth_uni@yahoo. on Wed, 04 May 2005 12:32
		Re: Latitude/longitude, contours, map_set, iMap? By: wmconnolley on Wed, 04 May 2005 12:15
		Re: Latitude/longitude, contours, map_set, iMap? By: Kenneth P. Bowman on Tue, 03 May 2005 20:05
		Re: Latitude/longitude, contours, map_set, iMap? By: David Fanning on Tue, 03 May 2005 19:40

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