The butterfly effect is overrated. There is always divergent behaviour in the long term, but most of the runs will come out very similar. In fact, it is a major

The butterfly effect is overrated. There is always divergent behaviour in the long term, but most of the runs will come out very similar. In fact, it is a major problem to introduce enough variation into the parameters of the ensemble run to capture the natural variation which is observed by the data acquisition systems. The US systems use vector breeding and European systems tend to use the singular vector method, which as I understand it is a bit more effective. http://journals.ametsoc.org/doi/abs/10.1175/2008MWR2498.1 http://journals.ametsoc.org/doi/abs/10.1175/2008MWR2498.1