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A Preliminary Verification of the A Preliminary Verification of the National Hurricane Center’s Tropical National Hurricane Center’s Tropical Cyclone Wind Probability Forecast Cyclone Wind Probability Forecast
ProductProduct
Jackie ShaferJackie ShaferScitor CorporationScitor Corporation
Florida Institute of Technology – Department of Marine and Florida Institute of Technology – Department of Marine and Environmental SystemsEnvironmental Systems
March 6, 2008March 6, 2008
22
OverviewOverview
IntroductionIntroduction MethodologyMethodology ResultsResults ConclusionsConclusions QuestionsQuestions
33
IntroductionIntroduction
Evaluate performance of Tropical Evaluate performance of Tropical Cyclone Wind Probability Forecast Cyclone Wind Probability Forecast ProductProduct
– Issued by National Hurricane CenterIssued by National Hurricane Center
– Related Study: Dr. John Knaff and Related Study: Dr. John Knaff and Dr. Mark DeMariaDr. Mark DeMaria
– Entire Atlantic Basin for 2006 Hurricane SeasonEntire Atlantic Basin for 2006 Hurricane Season
– This Project:This Project:– 2004 – 2007 Hurricane Seasons2004 – 2007 Hurricane Seasons– Florida East Coast: Jacksonville - MiamiFlorida East Coast: Jacksonville - Miami
MethodologyMethodology
44
Data CollectionData Collection 2004 Hurricane Season 2004 Hurricane Season
Provided by Dr. Mark DeMariaProvided by Dr. Mark DeMaria
2005 – 2007 Hurricane Seasons 2005 – 2007 Hurricane Seasons Provided by NHCProvided by NHC
55
Methodology cont’d…Methodology cont’d…
Determine if the wind speed criteria “occurred Determine if the wind speed criteria “occurred or “did not occur” during each forecast time or “did not occur” during each forecast time interval for each eventinterval for each event
34Kt
50Kt
64Kt
34Kt
50Kt
64Kt
12 h Forecast Interval: 0600z – 1800z on 09/04/2004
≥34Kt occurred in:• Cocoa Beach• Fort Pierce• West Palm Beach• Miami
≥34Kt did not occur in:• Jacksonville• Daytona Beach
66
Methodology cont’d…Methodology cont’d…
OccurredOccurred Did Not Did Not OccurOccur
Forecast % ≥ Forecast % ≥ ThresholdThreshold HitHit FAFA
Forecast % < Forecast % < ThresholdThreshold MissMiss CNCN
Classification of Probability Classification of Probability ForecastsForecasts
““HitHit”: Event Forecast to Occur, Event Occurred”: Event Forecast to Occur, Event Occurred ““MissMiss”: Event Forecast Not to Occur, Event Occurred”: Event Forecast Not to Occur, Event Occurred ““False AlarmFalse Alarm”: Event Forecast to Occur, Event Did Not Occur”: Event Forecast to Occur, Event Did Not Occur ““Correct NegativeCorrect Negative”: Event Forecast Not to Occur, Event Did Not ”: Event Forecast Not to Occur, Event Did Not
OccurOccur
Table 1: Contingency Table showing classification of each probability forecast
77
Methodology cont’d…Methodology cont’d…
Probability of Detection (POD): Probability of Detection (POD): The The fraction of the observed events that were correctly fraction of the observed events that were correctly forecastforecast
Probability of False Detection (POFD) Probability of False Detection (POFD) “False Alarm Rate”: “False Alarm Rate”: A measure of the A measure of the product’s ability to forecast non-eventsproduct’s ability to forecast non-events
Range: 0 to 1; Perfect Score: 1Range: 0 to 1; Perfect Score: 1
Range: 0 to 1; Perfect Score: 0Range: 0 to 1; Perfect Score: 0
88
Methodology cont’d…Methodology cont’d…
OccurredOccurred Did Not Did Not OccurOccur
Forecast % ≥ Forecast % ≥ ThresholdThreshold HitHit FAFA
Forecast % < Forecast % < ThresholdThreshold MissMiss CNCN
Table 1: Contingency Table showing classification of each probability forecast
Probability of Detection:Probability of Detection:
Probability of False Detection; “False Alarm Rate”:Probability of False Detection; “False Alarm Rate”:
99
100%
8% “Optimal Threshold”0%
1010
Methodology cont’d…Methodology cont’d…
OccurredOccurred Did Not Did Not OccurOccur
Forecast % ≥ Forecast % ≥ ThresholdThreshold HitHit FAFA
Forecast % < Forecast % < ThresholdThreshold MissMiss CNCN
Classification of Probability Classification of Probability ForecastsForecasts
““HitHit”: Event Forecast to Occur, Event Occurred”: Event Forecast to Occur, Event Occurred ““MissMiss”: Event Forecast Not to Occur, Event Occurred”: Event Forecast Not to Occur, Event Occurred ““False AlarmFalse Alarm”: Event Forecast to Occur, Event Did Not Occur”: Event Forecast to Occur, Event Did Not Occur ““Correct NegativeCorrect Negative”: Event Forecast Not to Occur, Event Did Not ”: Event Forecast Not to Occur, Event Did Not
OccurOccur
Table 1: Contingency Table showing classification of each probability forecast
1111
Forecast Interval Threshold 12 h 5% 24 h 10% 36 h 10% 48 h 12% 72 h 9% 96 h 4% 120 h 2%
Forecast Interval Threshold 12 h 2% 24 h 1% 36 h 4% 48 h 9% 72 h 2% 96 h 1% 120 h 1%
Forecast Interval Threshold 12 h 1% 24 h 5% 36 h 10% 48 h 9% 72 h 4% 96 h 3% 120 h 1%
1212
StatisticsStatistics
Probability of DetectionProbability of Detection Probability of False DetectionProbability of False Detection False Alarm RatioFalse Alarm Ratio Threat ScoreThreat Score Bias ScoreBias Score AccuracyAccuracy True Skill StatisticTrue Skill Statistic
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RangesRanges
Forecast Interval 34 50 64
(HR) (Kt) (Kt) (Kt)
12 100 100 100
24 99 94 71
36 92 71 47
48 76 46 28
72 48 25 13
96 40 22 11
120 20 10 6
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ConclusionsConclusions
The product performs wellThe product performs well Product shows high accuracy (0.98 to 0.66) between
12-Hr and 120-Hr, respectively Product adequately distinguishes observed events
from non-observed events: TSS ranges from 0.97 to 0.25 for the 12-Hr to 120-Hr,
respectively
Probabilities that may seem small or Probabilities that may seem small or unimportant are actually significantunimportant are actually significant
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So What?So What?
Results will be useful for:Results will be useful for: Operational decisions at CCAFS and KSCOperational decisions at CCAFS and KSC
Shuttle RollbackShuttle Rollback Payload ProtectionPayload Protection Personnel EvacuationPersonnel Evacuation
Risk Management Risk Management Evaluating Cost-Risk-Benefit Ratios for Evaluating Cost-Risk-Benefit Ratios for
evacuation decisionsevacuation decisions
Additional Areas of Interest:Additional Areas of Interest: Corpus Christi, TXCorpus Christi, TX New Orleans, LANew Orleans, LA Charleston, SCCharleston, SC
Questions?