SkewT/LogP Function for GrADS

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Download latest version: dated 21 March 2017.


The script incorporates all the basic features of standard skewt/logP plots, including:

Function Usage:

The explanation below assumes you are familiar with GrADS, its control files and data files.

The function takes a maximum of four arguments (temp, dewpoint, wind speed, wind direction); however, you need not enter all four. Use '-1' for each argument you are not passing.

The control (.ctl) file for the data file is not fundamentally different from other GrADS control files. For example, the following might be a control file from which you would plot a skewt in GrADS:

DSET ua.dat
TITLE Sample Control file for Skewt/LogP data - 100 grdpts and 11 levels at 10 hours
UNDEF -999
XDEF 10 LINEAR -70 1.0
YDEF 10 LINEAR 30 1.0
ZDEF 11 LEVELS 1000 925 850 700 500 400 300 250 200 150 100  
TDEF 10 LINEAR 00Z28Dec1996 1hr
temp 11 99 temperature data
dewp 11 99 dewpoint data
wspd 11 99 windspeed data
wdir 11 99 wind direction data

Your driver script in GrADS might look like:

"open ua.ctl"
"set t 4"
"set x 3"
"set y 5"
"set lev 1050 150"

function plotskew(sndtemp,snddewp,sndwspd,sndwdir)
. [rest of plotskew function available from this page]

Please note that you must set your dimensions to ONE POINT in X,Y,and T before running the plotskew script.

Sample Images:

Here is sample landscape mode output (portrait mode output is an option as well):

Questions and Problems:

Answers to common problems and questions can be found in a small FAQ.

Any remaining questions or problems with the function should be sent to:

Bob Hart
Florida State University Meteorology

Last Updated: 21 March 2017