Shading

[Kevin M Levey]

Hi Andy

cint (contour interval) only applies to contour lines, i.e. when you

set gxout contour

Shading intervals are set with

set clevs

see my example below:

Shading interval is determined by whatever you set up in your legend,  
i.e. (this is an example gs file : my_legend.gs)

*light blue to dark blue
'set rgb 41 200 255 255'
'set rgb 42 175 240 255'
'set rgb 43 130 210 255'
'set rgb 44  95 190 250'
'set rgb 45  75 180 240'
'set rgb 46  60 170 230'
'set rgb 47  40 150 210'
'set rgb 48  30 140 200'
'set rgb 49  20 130 190'
'set rgb 50  20 120 180'
'set rgb 51  20 110 170'

*light pink to dark rose
'set rgb 61 255 230 230'
'set rgb 62 255 200 200'
'set rgb 63 248 160 160'
'set rgb 64 230 140 140'
'set rgb 65 230 112 112'
'set rgb 66 230  80  80'
'set rgb 67 200  60  60'
'set rgb 68 180  40  40'
'set rgb 69 164  32  32'
'set rgb 70 134  32  32'
'set rgb 71 104  32  32'
'set rgb 72 74  32  32'

'set grads off'
'set timelab on'

'set clevs -25 -22.5 -20  -17.5  -15  -12.5  -10  -7.5  -5  -2.5   0    
2.5 5   7.5  10  12.5  15  17.5  20  22.5  25 '
'set ccols   51    50   49     48   47    46    45    44  43   42    
41   62  63  64  65   66    67  68    69  70     71  72'

Here my shading interval is 2.5.

If you wanted to plot contours + shading then you'd simply make cint  
2.5 as well.

set gxout shaded
d variable
set gxout contour
set cint 2.5
d variable
run my_legend.gs

You can define your own colors as I have above - you just need to know  
what the rgb values are. the limitations usually come

If you don't "run my_legend.gs" or if you don't specify set clevs and  
set ccols in your script, GRADS will use default colors and intervals  
and it will change from plot to plot depending on what the max/min  
values are. Using your own set colors and intervals will ensure the  
same legend range is used for all plots.

Hope this helps.

Regards,

Kevin M Levey, MSc in Oceans and Atmospheric Sciences (University of  
Cape Town)
Director of Meteorological Operations
CustomWeather, Inc.
San Francisco, California, USA

"Taking the World by Storm!"

http://www.customweather.com
http://www.myforecast.com
http://www.1stweather.com

cell: 415-794-0411
work: 415-777-3566
email: klevey at customweather.com

On Nov 11, 2009, at 11/11/09 - 9:03 AM, Andrew Revering wrote:

> In this example:
> http://portal.nccs.nasa.gov/cgi-d520_fp/geos5_wx.cgi
>
> The number of shade levels is ‘a lot’. So you get this look of  
> something very fluid, and hard to see one color to the next.
>
> I tried to set cint to 1 in my map, and it does not seem to be  
> contouring every 1 degree.
>
> Is this a limitation due to the number of defined colors (16) ? and  
> when its set to 1 there are too many levels and not enough colors?
>
> Or is there something else I need to do so that I’m able to contour  
> at a very frequent interval?
>
> Is there a way to have the default colors just circulate  
> automatically… IE, when you go through all the colors have it just  
> start over again, or is this done by default?
>
> Andy

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