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The HiDyn Model developed in "Long-Lead Prediction of Pacific SSTs
via Bayesian Dynamic Modeling" by L.M. Berliner, C.K. Wikle, and N.
Cressie (2000), Journal of Climate, 13, 3953-3968, uses
current values of SST anomalies, the Southern Oscillation Index (SOI),
and a summary of westerly surface-wind bursts as predictor variables.
Rather than viewing the prediction as restricted to a single model,
several linked statistical prediction models are developed. These models
condition on the current regime (Warm, Normal, or Cool), classified
according to the current value of SOI, and then provide probabilistic
forecasts of future regimes (Warm, Normal, or Cool)
seven months later. The probabilities
of the future regimes are estimated based on the current SOI and
wind-burst statistics. This model was trained on monthly data begining
in 1970.
The HiDyn-Model output is the predictive distribution for SST anomalies in the Tropical
Pacific, with a seven-month lead. Key summaries of this distribution
include (i) probabilities of each of the three temperature-regime states; and
(ii) SST mean-field estimates for each temperature regime. This page
shows (i) and (ii). When a probability-weighted average of the Warm,
Normal, and Cool mean-field estimates in (ii) is taken (with
probabilities given by (i)), we obtain (iii) a combined mean-field
estimate that yields the SST-field forecasts seen on most of the other
ENSO webpages.
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In these animations, each frame is based on data 7 months prior to the
forecast back to January-1970 data.
For example, the December-1985 forecast uses May-1985 data back to January-1970 data; the next frame
of the animation, namely
for January 1986, is based on all the data used to forecast December 1985, plus
the extra month of data for June 1985.
Click on the animation to pause it; click again to continue. A static image is obtained by choosing the start month and the
finish month to be the same. Also, choosing the finish month to pre-date the start month runs the animation in reverse order.
Note that to view these animations, Java needs to be enabled in your
browser.
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