Post on 12-Jan-2016
description
Extrem Forecast Index
Pierre Eckert
Daniel Cattani
MétéoSuisse
EFI: definition Scores and verification Precipitations Wind gust Conclusion
1
0
)()1( dppFpnEFI nfn
p
Ff(p)
An Extreme Forecast Index
Takes values from –1 (all members break climate minimum records) and +1 (all beyond climate maximum records)
For a single value (e.g. deterministic) forecast with climate rank Q: EFI3=(Q-50%) [1+4(Q-50%)2]
Q=95%, EFI3=0.81
Q=98%, EFI3=0.92
Q=99%, EFI3=0.96
Verification parameters (1) Precipitations (nov.2001-apr.2003)
Predictands: 2nd max prec. / 24h of climatological regions (W, E, S)
Predictors: EFI max over regions
Thresholds 10 mm/24h 20 mm/24h 50 mm/24h
Verification parameters (2) Gusts (nov.2001-apr.2003)
Predictands: 2nd max gust / 24h of climatological regions (W, E ) Predictors:
• EFI max over regions
• EFI max over all the domain (45-48.5°N; 5-11.5°E)
Thresholds 50 km/h 75 km/h 100 km/h
Verification: scores
Event Observed Not Observed
Forecasted A B
Not Forecasted C D
• Forecasted : EFI gt given value
• Hit Rate = A / (A+C)• FAR = B / (A+B)
Precipitations : Switzerland West
Prec ge 10mm/24h
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
False Alarm Rate
Hit
Ra
te T+66
T+90
T+114
T+138
Hit = 0,5EFI = 0,3 T+66hEFI = 0,2 T+90hEFI = 0,2 T+114
Precipitations : Switzerland West
Prec ge 20mm/24h
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
False Alarm Rate
Hit
Rat
e T+66
T+90
T+114
T+138
Precipitations : Switzerland West
Prec ge 50mm/24h
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
False Alarm Rate
Hit
Rat
e T+66
T+90
T+114
T+138
Precipitations : Switzerland South
Prec ge 10mm/24h
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
False Alarm Rate
Hit
Ra
te
T+66
T+90
T+114
T+138
Precipitations : Switzerland South
Prec ge 20mm/24h
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
False Alarm Rate
Hit
Rat
e T+66
T+90
T+114
T+138
Precipitations : Switzerland SouthPrec ge 50mm/24h
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
False Alarm Rate
Hit
Rat
e T+66
T+90
T+114
T+138
Gusts : Switzerland West
0
50
100
150
200
250
300
350
400
450
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
EFI - region W
T+48
T+72
T+96
T+120
50km/h
75km/h
Gusts : Switzerland West
0
50
100
150
200
250
300
350
400
450
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
EFI values - large dom ain
T+48
T+72
T+96
T+120
50km/h
75km/h
Gusts: Switzerland West
Gusts ge 50 km/h
0
0.2
0.4
0.6
0.8
1
1.2
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
False Alarm Rate
Hit
Rat
e T+48
T+96
T+48 domain
T+96 domain
Gusts: Switzerland West (ref region)
Gusts ge 75 km/h
0
0.2
0.4
0.6
0.8
1
1.2
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1
False Alarm Rate
Hit
Rat
e T+48
T+96
T+48 domain
T+96 domain
Conclusion: precipitations
T+42-66h
Hit=0.6
Prec ge 10mm Prec ge 20mm Prec ge 50mm
EFI FAR EFI FAR EFI FAR
West 0.2 0.2 0.2 0.6
East 0.2 0.3 0.2 0.7
South 0.3 0.3 0.3 0.5 0.5 0.5
Conclusion: Gusts
Gust ge 75 km/h
Hit=0.5
T+36-60h T+60-84h T+84-108h T+108-132h
EFI FAR EFI FAR EFI FAR EFI FAR
West (ref region) 0.3 0.7 0.3 0.5 0.2 0.7 0.2 0.8
West (ref domain) 0.8 0.7 0.7 0.7 0.5 0.8 0.3 0.9