'ave' zonal average PROBLEMS!

[Thomas Spengler]

Dear all,

I am using the function 'ave' to calculate zonal means of different
variables.

If you average over a latitude circle, following the documentation, you
should do:

ave(z,lon=0,lon=360,-b)   (1)

right?
The '-b' option enabling the weighting of the longitude '0' which is
included twice in the zonal average here.

Expression (1), following the GrADS documentation, should be identical to

ave(z,x=1,x=180)   (2)

right?

The problem ist though, that this is not the case! I get deviations of
the two results reaching 350 m^2 s^-2.
Does someone have the solution for calculating real, consistent zonal
averages with GrADS?
Or am I doing something wrong or didn't understand the documentation
properly?

Thanks in advance for your help and advice!

Cheers,
Thomas