Introduction of numerical Introduction of numerical

storm surge prediction modelsstorm surge prediction models

Dr.Wattana KanbuaDr.Wattana Kanbua Marine Meteorological CenterMarine Meteorological Center

Thai Meteorological DepartmentThai Meteorological Department

ContentsContents

• Features of Storm Surge Model Features of Storm Surge Model• Equations of the Storm Surge Model Equations of the Storm Surge Model• Treatment of Astronomical Tide Treatment of Astronomical Tide• Wind/pressure field Wind/pressure field• Pressure Field Estimation Pressure Field Estimation• Wind Field Estimation Wind Field Estimation• Specification of the Storm Surge Model Specification of the Storm Surge Model• Sources of Input Data Sources of Input Data• TC best track data TC best track data• SummarySummary

Features of Storm Surge Model 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.

Equations of the Storm Surge Mode Equations of the Storm Surge Modell

Equations of the Storm Surge Mode Equations of the Storm Surge Modell

Boundary Condition Boundary Condition

Treatment of Astronomical Tide Treatment of Astronomical Tide

• This model does not include astronomical tides, n - o 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 a dd astro nomical tides

Wind/pressure field 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 sto rm surge forecast.

Current NWP models have a tendency to estimate the maximum wind in a TC.

A parametric method makes TC “ensemble” manipulati on easier.

Pressure Field Estimation Pressure Field Estimation

Fujita’s formula Fujita’s formula

Wind Field Estimation Wind Field Estimation

Gradient wind relation

Add asymmetry

30Turn the wind vectors degree iii iiiii iiiiiiiii iiiiiiii iiiiii

Specification of the Storm Surg Specification of the Storm Surg e Model e Model

- Discretization: finite different method, explicit- G rid system: - staggered grid (C grid of Arakawa)- G -rid resolution (longitude latitude)- Number of grid- Time step

Sources of Input Data Sources of Input Data

• Forcing field (wind and pressure) – Typhoon Analysis Parameters

– Grid Point Values of Numerical Models ( GRIB1 f ormat )

• Bathymetric Data – SmithandSandwell, 2minutesmeshdata(http://topex.ucsd.edu/ )

TC best track data 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) are

a

ConclusionConclusion

• Awareness:Awareness:Ability to preventAbility to prevent enlightenmentenlightenment

• Forecast:Forecast: Track, Intensity, Rain, WindTrack, Intensity, Rain, Wind

• Collaboration:Collaboration:Typhoon Committee Typhoon Committee

RSMC TokyoRSMC Tokyo

AAcknowledgmentscknowledgments

I would like to express my sincere gratitude and deep appreciation to Mr. Masakazu HIG

AKI, Office of Marine Prediction Marine Divi sion Global Environment and Marine Depart ment Japan Meteorological Agency for his gu

idance, invaluable advice, supervision and material.