[gradsusr] Skip some stations when plotting station data

Rabah Hachelaf r.hachelaf at gmail.com
Wed Dec 30 23:51:41 EST 2015


*I would like to skip a **number of stations data when plot it with
grads.I find the message below describing a trick used in COLA, i am
wondering if this method still valid *

*or is there another **one.*


*Rabah  *

*Jennifer Adams* jma at cola.iges.org
*Thu Jan 20 10:16:09 EST 2011*

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Brian Doty has solved this problem with a C program that creates a
'filt' variable for the surface metars. The code does the following:
1) Assigns priorities to each report that are based on a combination
of the number of variables available and the intensity of precipitation
2) Filters out observations at a particular radius: first pass based
on priority, subsequent passes based on proximity to other obs.
3) All the obs are then written out with an extra data variable,
called 'filt', that you can use when drawing. The filt variable ranges
between 1 and 6.

For example,
'open  http://monsoondata.org:9090/dods/stn/metar/past48'
'set gxout stnmark'
'set lat 25 50'
'set lon -125 -65'
'd maskout(ts,filt-4)'   ;* draws fewer obs
'd maskout(ts,filt-2);   ;* draws more obs

We use Brian's code operationally at COLA (for the real time metars
behind our GDS) but cannot support it beyond that. Please write to me
offline if you would like a copy.

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