Control File?

[Matt Georgescu]

Fellow GrADS users,

I have a 50-year time series of July-Aug-Sep (JAS) precipitation means
calculated from a monthly long-term precip. dataset (01/1948 - 01/1998).
My interest was to calculate the JAS climatology from this monthly
dataset and plot only the JAS climatology.

The .ctl file that I use to open up the monthly dataset, calculate and
then plot the JAS climate, looks like:

dset ^./domainmean_daily.gdat
undef 1.0e30
options little_endian
title Monthly Averaged Arizona Precip
xdef  1 linear  1 1
ydef  1 linear  1 1
ZDEF 1 LEVELS 1
tdef    612 linear 00:00Z01jan1948 01MO

My question is this ... When I plot the JAS means, the values plotted
for each year are not displayed directly over the vertical axis that
corresponds to each individual year.  In other words, the value plotted is
slightly staggered - the value for 1960, for example, is displayed
slightly after 1960 (specifically, it is displayed on August 1960, as
that is the middle month of my 3-month average).

How can I force each value that is displayed to be plotted so that it
appears to correspond exactly to each individual year (ie January 1st of
each year)?

thanks,
matt