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A proposed new storm surge scale Pat Fitzpatrick, Yee Lau, Yongzuo Li, Nam Tran, and Chris Hill

A proposed new storm surge scale Pat Fitzpatrick, Yee Lau, Yongzuo Li, Nam Tran, and Chris Hill Geosystems Research Institute, Mississippi State University Saffir -Simpson scale does not account for: Ocean bathymetry Storm size Storm speed Sponsors: NOAA &

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A proposed new storm surge scale Pat Fitzpatrick, Yee Lau, Yongzuo Li, Nam Tran, and Chris Hill

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  1. A proposed new storm surge scale • Pat Fitzpatrick, Yee Lau, Yongzuo Li, Nam Tran, and Chris Hill • Geosystems Research Institute, Mississippi State University • Saffir-Simpson scale does not account for: • Ocean bathymetry • Storm size • Storm speed • Sponsors: NOAA & • Northern Gulf Institute

  2. 28,701 nodes, 54,792 elements

  3. Irish, J. L., D. T. Resio, and J. J. Ratcliff, 2008: The influence of storm size on hurricane surge, 38, J. Phys. Ocean., 2003-2013. Shallow Slope (1:1000) Slope 1:10000 They show surge varies by 30% for storm size, and that its most sensitive for intense hurricanes on shallow slopes

  4. Simulations assumed a wind profile based on Holland (1980) Where: p = pressure at radius r, ranging from central pressure pc to environmental pressure penv V = tangential wind speed B=scaling parameter that affects wind profile, typically varies from 0.5 to 2.0 A=function of Radius of Maximum winds (Rmax) and B Rmaxfrom Kimball and Mulekar (2004); Cat 1,3: 20-25 km, Cat 5:12-18 km =air density (1.15 kg m-3) Storm motion is included in V Winds are converted to u,v components, an inflow angle of 20 deg is assumed within 100 km, and 10 degrees otherwise Three storm sizes based on radius of tropical storm winds: 150, 250, and 350 km Three storm movement speeds: 5, 10, 15 mph Maximum winds: 85, 120, 155 mph

  5. Spreadsheet of 162 simulations ----- Example bathymetry influence -----Example size influence -----Example speed influence

  6. Bathymetry zone 5 Bathymetry zone 4 Bathymetry zone 3 Bathymetry zone 2 Bathymetry zone 1 One possibility is 3 scales with correction factor for speed

  7. Bathymetry zone 5 Bathymetry zone 4 Bathymetry zones 2-3 Bathymetry zone 1

  8. Powell and Reinhold (2007) have suggested using Integrated Kinetic Energy as a replacement to maximum sustained wind in the Saffir-Simpson scale The analytic solution for IKE based on Holland profile is: =Lower incomplete gamma function ; z =1 meter

  9. Overlap of large Cat 3 and avg Cat 5 for avg bathymetry

  10. Advantage: • One scale! • Linear trend • No “quantized” scale • Scale from 0.0 to 7.0

  11. How far east of center does inundation occur?

  12. Different Bathymetry, Different Intensity, Speed=15mph, Size=250km

  13. Shallow – Different Intensity, Different Size, Speed=10mph

  14. Hypothetical simulations for small, avg, large hurricanes were conducted for Cat 1, 3, 5, extended to slow-, avg-, and fast-moving storms for 6 bathymetries, resulting in 162 cases. • A new surge scale based on size is proposed for 5 bathymetry zones, resulting in 3 plots for reference. Speed can be added as a small correction term. • Integrated Kinetic Energy (which combines intensity and size) cannot be used by itself, but produces a linearly increasing surge trend for all bathymetries. It is proposed a 0-7 metric of this quantity be used as a singular, all-purpose surge scale for several bathymetric zones. • These cases also provide the ability to predict eastern inundation. Surge values level off with intensity, providing confidence for predicting the extent 5 and 10-ft inundation. • Shallow bathymetry doesn’t only result in higher surge, but extensive inundation east of storm. Conclusions

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