On North Atlantic Intedecadal Variability: A Stochastic View
175
Ensemble Trajeclories
300.0
200.0
100.0
0.0
1.0
-100.0
-200.0
-300.0
0.0
time
time
3CO
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o
1.0
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0.5
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0.0
630
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time
Ume
300
2.0
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1.5
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o
1.0
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620
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dme
time
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2.0 l
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.1
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o
1.0
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tlme
tlme
Fig. 9.20 Individual ensemble trajectories and ensemble mean (thick line) of projections
onto the frrst EOF of the North Atlantic 500 hPa geopotential height anomalies for the four
different forecast ensembles (Ieft) and time series of the respective normali sed ensemble
variances (right). The thick dashed lines show the temporal behavior of fitted first order
autoregressive processes. From Grotzner et al. (1999).