accumulation over time

[Irene Stemmler]

Dear all,

I want to accumulate area averages over time and plot them in a 2d plot.
I so far manage to plot instantaneous averages :

'set t 1 100'
'define avar=aave(var,global)'
'set lon 1'
'set lat 1'
'd avar'

but I want smth like

loop over t: avar(t)=avar(t-1)+aave(var(t),global)

I already tried to make use of "sum" and "tloop", but all I got was a
timeseries of the sum of the t+(t-1) values, I have problems in saving the
means in a way that I get t+(t-1)+(t-2)..+..

I could solve the problem using any other plotting tool or fortran, but I am
curious about how it works in GrADS.
Does anybody know the solution?

Thanks in advance

Irene