Is there any other method that one can use with GRADS apart from sqrt(ave(pow(ave(z,t=1,t=20)-z,2),t=1,t=20)). Thanks -------------- next part -------------- An HTML attachment was scrubbed... URL: http://gradsusr.org/pipermail/gradsusr/attachments/20111212/a0d3a98b/attachment-0003.html