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SLOSH

SLOSH. S ea, L ake, and O verland S urges from H urricanes. Part 1: W. Shaffer / MDL Part 2: B. Jarvinen / NHC. DEFINITIONS:. STORM SURGE is the increase in water level due to a storm (hurricane / tropical storm / high winds). STORM TIDE is the total water level during a storm

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SLOSH

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  1. SLOSH • Sea, • Lake, and • Overland • Surges from • Hurricanes Part 1: W. Shaffer / MDL Part 2: B. Jarvinen / NHC

  2. DEFINITIONS: STORM SURGEis the increase in water level due to a storm (hurricane / tropical storm / high winds). STORM TIDEis the total water level during a storm = Astro Tide + STORM SURGE + Rainfall Runoff + Anomaly

  3. b Storm tide 8.1 ft

  4. Storm tide 8.1 ft Predicted Tide 0.9 ft

  5. Storm tide 8.1 ft Storm Surge = Storm Tide – Predicted tide Predicted Tide 0.9 ft

  6. Storm tide 8.1 ft Storm Surge = Storm Tide – Predicted tide = 8.1 – 0.9 = 7.2 ft Predicted Tide 0.9 ft

  7. SLOSH Hurricane Storm Surge Model • Solves shallow water equations • Orthogonal curvilinear grid system • 2-dimensional (2 ½ dimensional ???)

  8. SLOSH Hurricane Storm Surge Model • Overland flooding • Sub-grid Features: • 1-dimensional flow for rivers and streams • barriers • cuts between barriers • channel flow, with chokes and expansions • Increased friction for trees and mangroves

  9. Individual Grid Barrier Stair Step Rise Water Surface above a square Transport Points Water Depth above a square Surge Points DATUM Dry and wetted grid squares. The squares are two-dimensional stair steps.

  10. Topo/BathyData Sources USGS LSU NGDC

  11. SLOSH Hurricane Storm Surge Model • Embedded parametric hurricane wind model • Uses a normalized wind profile • Solves diff eqn for wind speed and direction (Direction is NOT specified a priori) • Uses pressure, not observed wind speed • Forward speed incorporated into asymmetry

  12. SLOSH Hurricane Storm Surge Model • Universal, not “calibrated” to location • Utilizes “forecastable” hurricane parameters • Tested on MANY past hurricanes

  13. INPUT TO SLOSH TRACK Positions - latitude & longitude INTENSITY - (pressure drop) SIZE - Radius of maximum wind

  14. SLOSH Hurricane Storm Surge Model • Designed for hurricane evacuation planning • Used as input to hydrology’s DWOPER river model – forecast hydrograph at selected locations used to initialize wave which propagates up river • Being used for real-time surge forecasting near landfall time (beginning 24 hours before projected landfall)

  15. SLOSH Hurricane Storm Surge Model • Model output: • MOM’s and MEOW’s • Individual runs – in real time • Historical hurricane runs • Probabilistic surge forecasts • Available in • SLOSH display format • GIS format (ArcView or MapInfo) • Animations (on web)

  16. SLOSH Hurricane Storm Surge Model • Not included currently: • explicit tide computation • wave setup and runup

  17. http://www.nws.noaa.gov/mdl/etsurge/

  18. Verification of computed surges for past hurricanes

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