contour plot for diff latitudinal belts

[Arindam Chakraborty]

hi Suvarna,
        when grads reads a data file, (by default) the different
dimensions are read in this order: x, y, z, variable, t;
Means x (longitude) varies fastest, and then y (latitude) and so on.
(Although there can be variations of this, see
http://grads.iges.org/grads/gadoc/descriptorfile.html#VARS for
'non-standard binaries' for details. But for your control file the
standard rule applies).
        Now, one of your control files has y and z, for which first 8
data values in the file will be read as different latitudes at the
first level, and so on. For another control file, which has z and t,
the first 12 data values will be taken as different levels at the
first latitude (alias time here), and so on for the rest of
the data. This is the reason you get different results for those two
control files.
        How to write the control file is dependent on how you've
written down the data file. It is always a good idea to write the data
in the default order of grads if you plan to use it in grads later on.
In your case, you need to write y as the faster varying dimension
than z in your output data file. Then use the control file which has y
and z.
        Please also set the lat levels as 35, 25, ..., 5, -5, ..., 35
(the centers of the bands of average), that's a better way of
representation.





----------------------------
 ARINDAM CHAKRABORTY
 Department of Meteorology
 Florida State University
 Tallahassee, FL-32306, USA
 Tel: +001-850-6443524 (Off)
      +001-850-5758550 (Res)
 Fax: +001-850-6449642
____________________________

On Sat, 24 Jun 2006, Suvarna Fadnavis wrote:

> Dear Dr. Chakraborty,
>            I am trying to plot (Contor) QBO values obtaied at 8 latitudinal belts (40-
> 30, 30-20, 20-10, 0-10 10-0 10-20, 20-30, 30-40). I want to plot QBO values by taking
> x axis as latitude and y axais as pressure levels. I tried to plot it by taking
> (1) x-axis as time (t=8) and y -axis as pressure
> (2) x-axis as latitude and y -axis as pressure by defining ydef 8 levels -40 -30 -20 -
> 10  10 20 30 40
>             I should get the same structure but I get two different structure. Please
> guide me which is correct and what is the reason for difference. I am attaching ctl and
> gs and data file for your kinf perusal.
>             suvarna