problem with amean and aave

[Roger Shi]

Hi,

I am trying to plot a line graph of horizontal mean with z varying from
1000 to 100 mb.
I did the following

ga-> set z 1 19         ! means from 1000 to 100mb
ga-> set t 1
ga->  d  amean(qvapor,x=1,x=800,y=1,y=618)

and  got the error message

Operation error:  Invalid dimension environment
Looping dimension does not vary

if I did the following

ga-> set z 11         ! means for just 500mb
ga-> set t 1
ga->  d  amean(qvapor,x=1,x=800,y=1,y=618)
Result value = 0.00281046

This means that I can gat a area mean value for a single layer but I
can't get a line graph to show the vertical distribution. Is there any
way I can get a line graph to show horizontal mean with z varying from
1000 to 100 mb? I got the exact same error message with aave.

Thanks in advance,
Roger

--
=========================================================
Dr. Jainn Jong Shi (aka Roger)
Bldg 33 Rm C422
Code 613.1
NASA/Goddard Space Flight Center
Greenbelt, MD 20771
email: shi at agnes.gsfc.nasa.gov