So you want to plot the difference between a given variable at time t and the same variable at time t-1 for a range of time values? If so, then set your time dimension to encompass the entire period, then display:<br><br>
'd var - var(t-1)'<br><br>if Grads gives you any guff over that, try enclosing the expression in a tloop() function:<br><br>'d tloop(var-var(t-1))'<br><br>Jeff Duda<br><br><div class="gmail_quote">On Tue, Aug 7, 2012 at 10:57 AM, Haibin Li <span dir="ltr"><<a href="mailto:hli@envsci.rutgers.edu" target="_blank">hli@envsci.rutgers.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello there,<br>
<br>
I have a time series for a given geographic location, now I want to plot<br>
a time series map for the delta T, i.e.,<br>
Var(t=2)-Var(t=1),Var(t=3)-Var(t=2), ..., Var(t=end)-Var(t=end-1).<br>
Does anyone know what command I can use to achieve that purpose?<br>
Thanks.<br>
<br>
<br>
Haibin<br>
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</blockquote></div><br><br clear="all"><br>-- <br>Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br><br>