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Transcript of © 2005 Accurate Environmental Forecasting Climate and Hurricane Risk Dr. Dail Rowe Accurate...
© 2005 Accurate Environmental Forecasting
Climate and Hurricane Risk Climate and Hurricane Risk Climate and Hurricane Risk Climate and Hurricane Risk
Dr. Dail RoweDr. Dail Rowe
Accurate Environmental ForecastingAccurate Environmental Forecasting
www.accufore.comwww.accufore.com
© 2005 Accurate Environmental Forecasting
The Team
• This presentation is based on the work of a team of scientists at Accurate Environmental Foresting, Inc. and Climatek, Inc: – AEF
• Dr. Michael Dickinson • Dr. Dail Rowe
– Climatek• Dr. James Elsner (Florida State University)• Dr. Thomas Jagger
© 2005 Accurate Environmental Forecasting
Today’s Discussion
• Climate changes hurricane risk.– Regional risk changes by more then 200%
• Climate factors influencing hurricane activity:– El Niño – Southern Oscillation (ENSO)– North Atlantic Oscillation (NAO) – Atlantic Sea-surface Temperature (SST)
• Scientists generally agree on overall Atlantic basin activity.
• Recent innovations:– Regions at risk– Hurricane intensity– Translation from hazard to insured loss– Forecasting
© 2005 Accurate Environmental Forecasting
El-Niño / Southern Oscillation (ENSO)
El Niño (warm event)La Niño (cold event)
Sea surface temperature patterns in the eastern tropical Pacific Ocean change global weather patterns.
© 2005 Accurate Environmental Forecasting
ENSO Modulates Vertical Wind-shear
http://hurricanes.noaa.gov Hurricanes derive their power by transporting water vapor from the ocean surface up a natural chimney to the upper atmosphere.
Their strength relies on the existence of this chimney structure.
© 2005 Accurate Environmental Forecasting
ENSO Modulates Vertical Wind-shear
http://hurricanes.noaa.gov Weak wind-shear is conducive to hurricane development.
La Niña = weak shear and more hurricanes
© 2005 Accurate Environmental Forecasting
ENSO Modulates Vertical Wind-shear
http://hurricanes.noaa.gov Strong wind-shear disrupts hurricane structure.
El Niño = strong shear and fewer hurricanes
© 2005 Accurate Environmental Forecasting
North Atlantic Oscillation (NAO)
High NAOHigh NAO Low NAOLow NAO
NAO determines the strength of the atmospheric circulation in the Atlantic basin and is calculated as the difference in sea level pressures between Reykjavik, Iceland and Gibraltar.
Hurricanes that form in these conditions are more likely to travel westward towards the southern US.
© 2005 Accurate Environmental Forecasting
Atlantic Sea Surface Temperature
Warmer ocean surface temperatures promote hurricane growth and development.
© 2005 Accurate Environmental Forecasting
SST leads to decadal variability
Detrended May-June average SST anomalies
There is a clear multi-decadal signal in Atlantic Sea Surface Temperatures.
Casual analysis of the hurricane record shows a clear link between SST and hurricane activity.
© 2005 Accurate Environmental Forecasting
SST impact on hurricanes
Major hurricanes tracks from 1951-1998 stratified by SST
Cool Atlantic SST Warm Atlantic SST
© 2005 Accurate Environmental Forecasting
Cold vs. Warm SST Regimes
Major Hurricanes U.S. Landfalls Florida Landfalls Cold: 1900 - 1925: 32 8 2Cold: 1970 - 1994: 38 9 2 1.4 / yr 1 / 3 yrs 1 / 12.5 yrs
Warm: 1926 - 1969: 115 23 12 2.6 / yrs 1 / 1.3 yrs 1 / 2.1 yrs Warm: 1995 - 2004: 38 6 4 3.8 / yrs 1 / 1.7 yrs 1 / 2.5 yrs
© 2005 Accurate Environmental Forecasting
Modeling of Climate Factors and Hurricane Activity
• We employ a statistical modeling approach as in Elsner and Jagger (2004) and Elsner and Bossak (2005) to relate climate factors and hurricane activity.– Based on 130 year climate and hurricane records
• The Hurricane Climate Risk Index is a regional measure of the climate-conditioned annual hurricane probability relative to the averaged probability.
Probability in Climate of InterestAverage Probability
Index =
© 2005 Accurate Environmental Forecasting
Consensus and Innovation
• Most agree on projections of overall Atlantic Basin hurricane activity for the upcoming season.
• Innovations are occurring– Regions at risk– Storm intensity– Forecasting– Translation from hazard to insured loss
Intensity AEF NOAA TSR CSU Average
Named Storms 13.2 12-15 13.9 15 9.9
All Hurricanes 7.5 7-9 7.8 8 6.0
Major Hurricanes 3.7 3-5 3.6 4 2.6
© 2005 Accurate Environmental Forecasting
Hurricane Index: 1938
Climate SST NAO ENSO ENSO Trend
Factors: 0.21 0.31 -0.65 -0.23
Category 3-5 HurricanesCategory 1-5 Hurricanes
© 2005 Accurate Environmental Forecasting
Hurricane Index: 1989
Category 3-5 Hurricanes
Climate SST NAO ENSO ENSO Trend
Factors: 0.08 0.32 -0.73 0.36
© 2005 Accurate Environmental Forecasting
Hurricane Index: 1994
Category 3-5 Hurricanes
Climate SST NAO ENSO ENSO Trend
Factors: -0.11 0.78 0.33 0.31
© 2005 Accurate Environmental Forecasting
Hurricane Index: 2004
2004 was moderately risky for hurricanes in general, but…
All hurricanes
SST: 0.31
NAO: -0.51
ENSO: 0.24
ENSO Trend: 0.58
© 2005 Accurate Environmental Forecasting
Hurricane Index: 2004
2004 was moderately risky for hurricanes in general, but…
it was VERY risky for extreme events in the southeast US.
All hurricanes
Cat 4-5 hurricanesCat 3.5-5 hurricanes
SST: 0.31
NAO: -0.51
ENSO: 0.24
ENSO Trend: 0.58
© 2005 Accurate Environmental Forecasting
Climate Forecasts
• ENSO and Atlantic SST forecasts have useful skill at lead times of at least 9 months.– Good Florida to Maine risk forecasts well in advance
of the hurricane season.
• Forecasts of summer NAO conditions are less skillful.– Forecasts of Gulf of Mexico activity improve just prior
to the hurricane season.
© 2005 Accurate Environmental Forecasting
Insured Loss and Climate
• The climate induced changes in hurricane frequency and severity indicated by the Index can be used to modify the frequency and severity assumptions governing the creation of the synthetic events sets commonly used to probabilistically evaluate hurricane related insured risk.
• AIR and AEF have recently integrated our Index technology with AIR’s hurricane catalog to produce forecasts of how climate variability will affect the probability of insured loss during the upcoming hurricane season.
© 2005 Accurate Environmental Forecasting
Insured Loss and Climate
Damage Assessment
Synthetic Hurricane Event Set
Insured Loss Estimation
© 2005 Accurate Environmental Forecasting
Insured Loss and Climate
Damage Assessment
Synthetic Hurricane Event Set
Insured Loss Estimation
18 39
© 2005 Accurate Environmental Forecasting
Insured Loss and Climate
Damage Assessment
Synthetic Hurricane Event Set
Insured Loss Estimation
18 39
Climate induced changes in Loss Exceedance Curves
© 2005 Accurate Environmental Forecasting
Conclusions
• Climate variability modifies both the frequency and severity of hurricanes on a regional basis.– Regional changes of more then 200%– El Niño, the North Atlantic Oscillation, and Atlantic
sea-surface temperature are all important factors
• The AEF/AIR Climate Conditioned Hurricane Catalog permits users to evaluate the effect of climate variability on their hurricane related exposure.