1. Introduction of numerical storm surge prediction models Dr.Wattana Kanbua Marine Meteorological Center Thai Meteorological Department

2. Contents Features of Storm Surge ModelFeatures of Storm Surge Model Equations of the Storm Surge ModelEquations of the Storm Surge Model Treatment of Astronomical TideTreatment of Astronomical Tide Wind/pressure fieldWind/pressure field Pressure Field EstimationPressure Field Estimation Wind Field EstimationWind Field Estimation Specification of the Storm Surge ModelSpecification of the Storm Surge Model Sources of Input DataSources of Input Data TC best track dataTC best track data SummarySummary

3. Features of Storm Surge Model Based on two-dimensional shallow water equations Less computer requirement Thus, users can specify high horizontal resolution (1-2 minutes lat-lon) Suitable for the countries which have complicated coast lines.

4. Equations of the Storm Surge Model

6. Boundary Condition

7. Treatment of Astronomical Tide This model does not include astronomical tides, no tide-generating force or forcing on boundary The model can compute only storm surges. Pick up time series of storm surge from point which want to predict and add astronomical tides

8. Wind/pressure field There are two options to estimate the field: grid point values of numerical weather prediction models a parametric method with some empirical relations A parametric method is used for TMD’s operational storm surge forecast. Current NWP models have a tendency to estimate the maximum wind in a TC. A parametric method makes TC “ensemble” manipulation easier.

9. Pressure Field Estimation Fujita’s formula

10. Wind Field Estimation Gradient wind relation Add asymmetry Turn the wind vectors 30 degree inward to reproduce cyclonic inflow

11. Specification of the Storm Surge Model - Discretization: finite different method, explicit - Grid system: staggered grid (C-grid of Arakawa) - Grid resolution (longitude-latitude) - Number of grid - Time step

12. Sources of Input Data Forcing field (wind and pressure) – Typhoon Analysis Parameters – Grid Point Values of Numerical Models (GRIB1 format) Bathymetric Data – Smith and Sandwell, 2minutes mesh data (http://topex.ucsd.edu/ )

13. TC best track data These files include the following analyzed values: position and moving velocity of TC center atmospheric pressure of TC center maximum wind velocity radius of gale wind (more than 50kt) area radius of severe wind (more than 30kt) area

14. Conclusion Awareness: Ability to prevent enlightenmentAwareness: Ability to prevent enlightenment Forecast: Track, Intensity, Rain, WindForecast: Track, Intensity, Rain, Wind Collaboration: Typhoon CommitteeCollaboration: Typhoon Committee RSMC Tokyo

15. Acknowledgments I would like to express my sincere gratitude and deep appreciation to Mr. Masakazu HIGAKI, Office of Marine Prediction Marine Division Global Environment and Marine Department Japan Meteorological Agency for his guidance, invaluable advice, supervision and material.