basemap

[Teresa Joan Parker]

On Mon, 16 Mar 2009 09:15:06 -0400, Jennifer Adams <jma at COLA.IGES.ORG> wrote:

>Hi, Tess --
>The basemap.gs script is drawing a lot of polygons that fit exactly
>inside (or outside) the continental outlines. The database of polygon
>coordinates was generated by running another script manually -- it was
>a painstaking process that required the effort of several summer
>interns. Unfortunately, some of the polygons in the database cross
>over latitude circles and this spoils the look of some circular polar
>stereographic plots because these polygons do not get clipped. There
>are a couple of options:
>1. Try changing your latitude limits -- maybe there are no polygons
>crossing the 65N line...
>2. Use low resolution instead of medium -- I think these polygons are
>better behaved
>3. (Best option, I think) Change your lat range to 50 90, but then use
>'set mpvals 0 360 70 90' to zoom into the area of interest -- this
>will result in a square plot instead of a circular one, but basemap
>will work properly. You can rotate the plot by changing the min/max
>lon values in the 'set mpvals' command.
>
>Jennifer
>
>
>On Mar 15, 2009, at 9:05 PM, Tess Parker wrote:
>
>> List - I am using the script basemap.gs to produce a north pole
>> stereographic map with land areas shaded grey. I am using medium
>> resolution.
>> My grads commands are:
>>
>> 'open avestn.ctl'
>> 'enable print 'test_ave.gmf'
>> 'set grads off'
>> 'set mproj nps'
>> 'set lon 0 360'
>> 'set lat 70 90'
>> 'set digsize 0.09'
>> 'set dignum 1'
>> 'set stid on'
>> 'set stnprint on'
>> 'set mpdset mres'
>> 'set map 1 1 3'
>> 'd press'
>> 'basemap L 15 0 M'
>> 'draw title Monthly Mean SLP'
>> 'print'
>> 'disable print'
>>
>> The problem I have is that there are a couple of shaded areas which
>> extend
>> outside my map; do I need to use another command such as mpvals or
>> something
>> to get rid of these? There are three biggish blocks of grey outside
>> the 60
>> lat circle. Any help much appreciated.
>
>--
>Jennifer M. Adams
>IGES/COLA
>4041 Powder Mill Road, Suite 302
>Calverton, MD 20705
>jma at cola.iges.org
>
>
>
>

Thanks so much Jennifer, that works really well. Options 1 and 2 still had
"rogue" polygons, unfortunately (I bet those summer interns worked hard at
them!) but option 3 works very well. I'm not sure about your comment on
rotating the plot using the lon min/max values in the 'set mpvals' command
though; as this is set to 0 and 360 respectively, how could I change it? I
tried 360 and 0 but this obviously didn't work! Any suggestions?