Re: min and max contours

[Andrew Wittenberg <andyw@xxxxxxxxxxxxxxxxxxxx>]

On Thu, 22 Mar 2001, Glenn Carver wrote:
> what I need to be able to do is :
> 
>   minvalue -> 1, 1->2, 2->3, ... 9->10, 10->max value.
> 
> My problem is that I'm comparing plots from different models and I need
> to use the same scale. With data that goes outside the range 1->10 (say), 
> Ferret leaves it blank. Programs like GrADS or gsharp will contour from
> min->max with a specified set of levels and I need to be able to do the
> same with Ferret. I've been through the documentation but I don't think
> it's possible?   

Hi Glenn,

The simplest way is to specify extra contours beyond the range of your
data:

yes? fill/lev=(-1000)(1,10,1)(1000) data

This will give -1000->1, 1->2, 2->3, ... 9->10, 10->1000.  

If you actually want to see the min and max on the plot, here's one way to
do it.  First define variables to contain the min and max of a dummy
variable called "data":

let min = data[x=@min,y=@min]
let max = data[x=@max,y=@max]

Then define "data" and plot it, say for February SST in the tropical
Pacific:

use coads_climatology 
let data = sst[x=120E:90W,y=20S:20N,l=2]
fill/lev=(`min`)(24,28,1)(`max`) data

The min/max definitions will change automatically as the definition of
"data" changes, so you can now do another plot, say of April sea level
pressure, using:

let data = slp[x=120E:90W,y=20S:20N,l=4]
fill/lev=(`min`)(1010,1016,1)(`max`) data

Hope that helps,

Andrew

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Andrew Wittenberg          Program in Atmospheric and Oceanic Sciences
andyw@splash.princeton.edu                        Princeton University
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