multi-year monthly mean standard deviation

[LAURA FEUDALE]

Dear Simon,
the aave function doesn't work when time is a varying dimension. In this
case you should use the "tloop" function.
So try adding the tloop function in this way:

.....
'd tloop(sqrt(ave(aave(pow(ztemp-tmp.2,2),lon=36,lon=54,lat=51,lat=65),t+396,t=528,12)))'
'd tloop(sqrt(ave(aave(pow(zprec-pre,2),lon=36,lon=54,lat=51,lat=65),t+396,t=528,12)))'

Regards,

-- Laura

----------------------------------------------------------------------
  Laura Feudale, Ph.D. (Climate Dynamics, George Mason University/COLA)
*Current Affiliation:            Earth System Physics Section
  The Abdus Salam International Centre for Theoretical Physics
                         Trieste, ITALY
----------------------------------------------------------------------



On Tue, 3 Apr 2007, Simon Krichak wrote:

> Dear Experts,
>
>  I am trying to calculate mean multiyear standard deviations from
>  monthly mean data on temperature and precip.
>
> To do it I apply the following script:
>
> 'open  ../CRU-DATA/GRADS:1951-2000.pre.ctl '
> 'open  ../CRU-DATA/GRADS:1951-2000.tmp.ctl '
> 'set x 1'
> 'set y 1'
> 'set t 1 12'
> 'set tlsupp year'
> 'define ztemp=ave(aave(tmp.2,lon=36,lon=54,lat=51,lat=65),t+396,t=528,12)'
> 'define zprec=ave(aave(pre,lon=36,lon=54,lat=51,lat=65),t+396,t=528,12)/30'
> 'd
> sqrt(ave(aave(pow(ztemp-tmp.2,2),lon=36,lon=54,lat=51,lat=65),t+396,t=528,12))'
> 'd
> sqrt(ave(aave(pow(zprec-pre,2),lon=36,lon=54,lat=51,lat=65),t+396,t=528,12))'
>
> And obtain the following diagnostics:
>
> ga-> stand-deviation.gs
> Syntax Error:  Invalid dimension expression
>  Cannot use an offset value with a varying dimension
>  Varying dimension = 3
> Error from AVE:  1st dimension expression invalid
> Operation Error:  Error from ave function
>  Operation Error:  Error from sqrt function
>  Error ocurred at column 1
>  DISPLAY error:  Invalid expression
> Expression =
> sqrt(ave(aave(pow(ztemp-tmp.2,2),lon=36,lon=54,lat=51,lat=65),t+396,t=528,12))
> Syntax Error:  Invalid dimension expression
> Cannot use an offset value with a varying dimension
> Varying dimension = 3
> Error from AVE:  1st dimension expression invalid
> Operation Error:  Error from ave function
> Operation Error:  Error from sqrt function
>  Error ocurred at column 1
>  DISPLAY error:  Invalid expression
>  Expression =
> sqrt(ave(aave(pow(zprec-pre,2),lon=36,lon=54,lat=51,lat=65),t+396,t=528,12))
>
>
> I do not understand my mistake unfortunately.
> Please kindly let me know your recommendations.
>
> Thanks.
>                    Simon Krichak
>
>