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RA VI Clips Workshop. Verification of Probabilistic Forecast. J.P. Céron – Direction de la Climatologie S. Mason - IRI. The Exercise. identify the forecasts of El Niño, Neutral, and La Niña years. L. E E E E E.

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Verification of probabilistic forecast

RA VI Clips Workshop

Verification of Probabilistic Forecast

J.P. Céron – Direction de la Climatologie

S. Mason - IRI


The exercise
The Exercise

  • identify the forecasts of El Niño, Neutral, and La Niña years

L

E E E E E

E L


The exercise1
The Exercise

  • identify the forecasts of El Niño, Neutral, and La Niña years


The exercise2
The Exercise

  • calculate forecast probabilities for El Niño, neutral, and La Niña events

0 % 80 % 20 %

100 % 0 % 0 %

20 % 60 % 20 %


The exercise3
The Exercise

  • calculate forecast probabilities for El Niño, neutral, and La Niña events


The exercise4
The Exercise

  • calculate forecast biases

20 % - 33 %

The frequency of La Niña forecasts is 18 / (18*5) = 0,20

The observed frequency of La Niña events is 6 / 18 = 0,33


The exercise5
The Exercise

  • calculate forecast biases


The exercise6
The Exercise

  • calculate the Hit Rate and False Alarme Rate

1,00 1,00

0,83 0,25

0,83 0,00

0,50 0,00

0,50 0,00

0,17 0,00


The exercise7
The Exercise

  • calculate the Hit Rate and False Alarme Rate


The exercise8
The Exercise

  • ROC diagram


The exercise9
The Exercise

  • ROC diagram


The exercise10
The Exercise

  • Brier skill scores

  • Differences between the ROC areas and Brier skill scores

    • The ROC areas indicate more optimistic estimates of forecast skill, most notably for the neutral conditions.

    • The Brier skill score indicates negative skill for forecasts of neutral conditions. The Brier skill scores for this category are weak because of the large forecast bias, but the ROC ignores the bias.


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