JP1.43
Improved Measures of Hurricane Hurricane Destructive Potential Based on Integrated Kinetic Energy
Mark D. Powell, NOAA/AOML/HRD, Miami, FL
On the day following Hurricane Katrina's landfall, Mr. Jim Holt of Biloxi MS commented: “It looks like Hurricane Camille killed more people yesterday than it did in 1969.” Apparently some personal evacuation and storm preparation decisions were made based on comparing Hurricane Katrina to Hurricane Camille, since both were Saffir-Simpson category five storms a day prior to landfall. People were familiar with the areas that Camille had flooded, and perhaps felt that Katrina was incapable of exceeding Camille's damage, despite warnings of extreme storm surge and waves. Katrina, however was much larger than Camille, greatly increasing it's capacity to inflict damage.
Hurricane damage potential, as currently defined by the Saffir-Simpson scale and the maximum sustained surface wind speed in the storm, fails to consider the area impact of winds likely to force surge and waves or cause particular levels of damage. To demonstrate the importance of storm size, we compared the integrated kinetic energy of Hurricanes Camille and Katrina. While both storms achieved Category five status, Katrina on the day before landfall exhibited twice the integrated kinetic energy for winds > hurricane force. At landfall, Katrina weakened to Cat 3 status but the expansion of the wind field allowed the integrated kinetic energy to be maintained at the same level as when a Cat 5, resulting in large losses due to storm surge, wave, and wind damage. When communicating hurricane awareness, it is important not to focus primarily on the Saffir-Simpson Category or storm intensity... the combination of storm size and intensity govern the potential for storm damage. Integrated kinetic energy represents a framework that captures the physical process of ocean surface stress forcing waves and surge while also taking into account structural wind loading and the spatial coverage of the wind. Integrated kinetic energy was computed from gridded, objectively analyzed surface wind fields of 23 hurricanes representing large and small storms. A wind destructive potential rating was constructed by weighting wind speed threshold contributions to the integrated kinetic energy, based on observed damage in Hurricanes Andrew, Hugo, and Opal. A combined storm surge and wave destructive potential rating was assigned according to the integrated kinetic energy contributed by winds greater than tropical storm force. The ratings are based on the familiar 1-5 range, with continuous fits to allow for storms as weak as 0.1 or as strong as 6. IKE and wind and surge destructive potential ratings are now included on the NOAA-AOML Hurricane Research Division experimental research wind field products available at www.aoml.noaa.gov/hrd/data_sub/wind.html
Joint Poster Session 1, Tropical Cyclones and Probability/Statistics Posters
Monday, 21 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B
Previous paper