Parameter Table

[Eric Altshuler]

Michel,

It is not possible to create a grib file in grads using fwrite. You can only write a direct access binary file, or a sequential binary file if you use 'set fwrite -sq <filename>'. The fwrite file is binary data only and has no metadata. If you want to create a grib file in grads, I think you need to use lats4d which I'm not very familiar with.

To create a blank map in grads with grid lines, there is a trick you can use. Choose any variable to display, and choose a contour level outside the range of values for that variable. For example, if you choose sea level pressure (slp), do the following:

'set gxout contour'
'set clevs 0'
'd slp'

You should get a map, with grid lines but no contours since slp is always much greater than 0.

Best regards,

Eric L. Altshuler
Assistant Research Scientist
Center for Ocean-Land-Atmosphere Studies
4041 Powder Mill Road, Suite 302
Calverton, MD 20705-3106
USA

E-mail: ela at cola.iges.org
Phone: (301) 902-1257
Fax: (301) 595-9793


----- Original Message -----
From: "Michel dos Santos Mesquita" <mmeclimate at MAC.COM>
To: GRADSUSR at LIST.CINECA.IT
Sent: Wednesday, March 19, 2008 12:13:28 PM GMT -05:00 US/Canada Eastern
Subject: Parameter Table

Hi everyone,

I'm trying to use grib2ctl to create a control file to a variable I
had saved in grib format in GrADS. I saved the variable using the
fwrite command. This variable was created in GrADS from another grib
file that I had opened previously. The original grib file had a
parameter table.

Grib2ctl uses the file's parameter table to identify the
characteristics of my data, right? However, saving a grib file using
GrADS does not produce a parameter table. For example, if I use wgrib
to read my file created from GrADS, nothing is displayed.

How can I create a parameter table for the variable I am saving in
GrADS and how can I incorporate the table into the grib file?

I have another question, I'm plotting some trajectories, and I need to
plot them on an a map with no other data (empty map). If I type 'draw
map', it draws the map without gridlines, lat, lon, etc. I'm plotting
the trajectories using 'draw line' only. How can I create an empty map
with all of the characteristics of  a 'normal' map in GrADS?

I thank you in advance!

Kindest regards,


Michel Mesquita
http://web.mac.com/mmeclimate