R.H. Weisberg and L. Zheng FWRI Marine Quest 04/09/05
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Transcript of R.H. Weisberg and L. Zheng FWRI Marine Quest 04/09/05
A Numerical Simulation of the Hurricane Charley Storm Surge in the Light of Lessons
Learned from Tampa Bay
R.H. Weisberg and L. Zheng
FWRI Marine Quest
04/09/05
Submergence based on a 5-foot uniform sea level rise
Submergence based on a 10-foot uniform sea level rise
Submergence based on a 20-foot uniform sea level rise
Hurricane Storm Surge Simulation Requirements
1) A high resolution numerical circulation model with capabilities for flooding and drying land.
2) Accurate wind and pressure fields.
3) High resolution bathymetry and elevation data.
Hydrodynamic Model: FVCOM
3) Incorporating flooding/drying skill which is critical for storm surges study.
Advantages:
1) Using unstructured triangle grid to better represent complex coastal and estuarine geometry.
2) Using simple finite-difference which has simple discrete structures and computational efficiency.
Prototypical Hurricane Structure (Holland, 1980)
Merged bathymetry and topography
Lessons learned from Tampa Bay
Based on prototypical category 2 and 4 storms that approach the region from several different directions, at different approach speeds, and making landfall at different locations.
http://ocg6.marine.usf.edu
Model Grid for Tampa Bay Storm Surge Experiment
Minimum resolution: 100 m
Category 2 storm translating at 5 m/s
Courtney Compbell Causeway
W. Howard Frankland Bridge
Gandy Bridge
Sunshine Skyway B
ridge
24 Hour
OCG @ USF
St. Pete
Tampa
28 Hour
OCG @ USF
Tampa
St. Pete
30 Hour
OCG @ USF
St. Pete
Tampa
Case I: IRB landfall from the west.
Case II: Translation up the Bay.
Case III: Coast parallel from the south Case IV: Coast parallel from the north
Arrow: landfall time
Courtney Compbell Causeway
W. Howard Frankland Bridge
Gandy Bridge
Sunshine Skyway B
ridge
Category 2 storm translating at 5 m/s
Case I: IRB landfall from the west.
Case II: Egmont Key.
Case III: Sarasota Case IV: Tarpon Springs
Arrow: landfall time
1. 5 m/s (10 knot)
2. 10 m/s ( 20 knot)
3. 2.5 m/s ( 5 knot)
Category 2 storm making landfall at Indian Rocks Beach from the west with speeds of
IRB landfall from the west withtranslation speeds of:
5 m/s,
10 m/s, and
2.5 m/s.
Arrow: landfall time
1. Category 2
2. Category 4
Storm making landfall at Indian Rocks Beach from the west with speeds of 5 m/s
30 Hour
OCG @ USF
Tampa
IRB landfall from the west at5 m/s for: category 2
category 4. Arrow: landfall time
The Surge in Tampa Bay Is Sensitive to:
1) the storm intensity;
2) the landfall location;
4) the direction of approach.
3) the speed of approach; and
Hurricane Charley Storm Surge Simulation
Big Carlos Pass
Ft. Myers
Sanibel Is.
Captiva
N. Pine Is.
Punta Gorda
E. side of CHW. side of CH
Courtesy of T. Liebermann
Summary1) Based on the lessons learned from Tampa Bay experiments we explain the relatively small H. Charley surge by virtue of:
• The approach direction from SW to NE and subsequent translation up the estuary.
• The rapid approach speed (16 knots).
• The small storm radius (10~20 km).
2) We account for the breach at North Captiva Island by the large across-barrier-island sea level gradient that occurred as the H. Charley passed by.
Acknowledgments
This work was supported by the Office of Naval Research, grants # N00014-98-1-0158 and N00014-02-1-0972 and by the U.S. Geological Survey, order # 4-SPSA-11920. Changsheng Chen (UMassD) kindly shared the FVCOM code, and Timothy Liebermann (SFWMD) kindly shared the CH merged bathymetric and topographic data set.