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20031106: GAREA <> GAREA?

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  • Subject: 20031106: GAREA <> GAREA?
  • Date: Thu, 6 Nov 2003 11:15:20 -0700 (MST)
Rob,

When you specify an upper right point so close to the pole, you
will be very sensitive to the convergence of longitudes such that a
small change in latitude makes a large difference in your plot.

An example of an area for Canada is provided in the
$GEMTBL/stns/geog.tbl with garea=37.90;-120.40;58.60;-14.00, and could be
quickly used with:

GAREA=cn
PROJ=def

The default projection would specify STR/0-;-95;0, but it serves as
a starting point to explain projections. Also see:
http://my.unidata.ucar.edu/content/software/gempak/tutorial/projections.html

Steve Chiswell


On Wed, 5 Nov 2003, Robert P Dale wrote:

> I'm trying to match up some backgrounds I already have created, and am
> finding out that the numbers I'm putting into GAREA are rarely duplicated in
> the actual output... For example, to do Canada I have:
>
> garea=40;-142;88;-46
> proj=lea/64;94;0
>
> which on mapmaker brings me a nice map of Canada. In gpmap it gives me a
> weird half of western Canada. If I change some of the above numbers by a few
> degrees either way, it'll fill up the screen entirely and give me closer to
> what I want, or reduce the proportions and make things worse. Am I missing
> something else in the pursuit of the right map?
>
>  - Rob
>