SURA Super-Regional Testbed on Coastal SURA Super-Regional Testbed on Coastal Inundation – Extra-tropical StormInundation – Extra-tropical Storm

Harry V. Wang, Yi-cheng Teng, Yanqiu Meng and Derek LoftisHarry V. Wang, Yi-cheng Teng, Yanqiu Meng and Derek Loftis

Virginia Institute of Marine ScienceVirginia Institute of Marine ScienceThe College of William & MaryThe College of William & Mary

Joseph ZhangJoseph Zhang

Oregon Health and Science UniversityOregon Health and Science UniversityNSF Land and Water Margin Research CenterNSF Land and Water Margin Research Center

SURA super-regional testbed meeting on coastal inundation SURA super-regional testbed meeting on coastal inundation 03-07-201103-07-2011

OutlineOutline

1. SELFE set up

2. Analysis of surge and tides results for V2.0

Case studied: 2005 and 2007 storms

3D results without wind wave

Preliminary results with wind wave

3. What is WWM? (Dr. Yinglong Joseph Zhang)

Results Analyses Plan for the Inundation Testbed v2.0

• Tides:

• Datum adjustment = 0 m (NAVD88 approx = MSL using reference in Boston and Plymouth, baroclinic / sterric effects in open BC forcing)

• Forcing: July – August 2010 elevation time series provided by UMassD (predicted by the Gulf of Maine FVCOM tidal model with inclusion of five major tidal constituents-M2, N2, S2, K1 and O1).

• Runs: 2D Mannings n = 0.025 3D run, 11 vertical layers, quadratic bottom friction using:• Where zab = height of the lowest grid cell above the bottom and zo is a function of

depth:• Note, inside Scituate, H < 40 m, and therefore zo should =0.003 m.

• Analysis: model elevation time series at Scituate NOAA gauge – location/data provided by UMassD

• Skill: IMEDS – time series comparisons for elevation• Model – Model Comparisons• from skill assessment

- extra-tropical domain

Set Up for 2D and 3D mode SELFE model Set Up for 2D and 3D mode SELFE model

• Model domains: Situate a domain

• Tidal boundary conditions: M2, K1, O1, S2, N2, provided by FVCOM

• Time step = 180 s, total run time = 45 days

• For 2D, Manning n=0.025 was used. For 3D, Vertical 11 S-layers were used;

• The wind forcing 9x9 km WRF wind at 10 m height.

• The model and data comparison was conducted for May 2010

City of Scituate modeling domainCity of Scituate modeling domain

**SELFE-WWM used 21 frequencies and 24 angles to simulate wind waves

WWM II (Wind Wave Model)WWM II (Wind Wave Model)• The Wind Wave Model is one of the first 3rd generation spectral

wave models, which solves the Eulerian form of the Wave Action Equation on unstructured meshes.

• The Model was developed in cooperation between the National Cheng Kung University, Taiwan (Dr. Hsu) and the Technical University of Darmstadt, Germany (Drs. Roland and Zanke). The Motivation was the inflexibility of freely available spectral wave models to discretize complicated domains.

• The numerical schemes of the WWMII (Roland, 2009) will be available in WWIII V4.0

• The WWMII was successfully coupled to SELFE to account for the effect of waves on circulation

Physics in the WWMIIPhysics in the WWMII

The WWM II incorporates:

• SWAN Model deep and shallow water physics • WAM Model (ECMWF Version)• Fabrice Ardhuin’s of deep water physics (see JCOMM Project (

http://www.jcomm-services.org/Wave-Forecast-Verification-Project.html)

Numerical schemes in the Numerical schemes in the WWM IIWWM II

• Operator Splitting Methods (OSM) e.g. WWIII or WWM

– 1st Step – Spectral part

– 2nd Step – Geographical space

– 3rd Step – Integration of the source terms

*

*000; on 0,t

Nc N N N t

t

**

* ** *00; on 0,t t t

Nc N N N t

t

***

** ** *** **00 ; on 0,x y t t t

Nc N c N N N t

t x y

****

**** ***,** 0; on 0,totN t t t

NS N N t

t

Numerical schemes in the WWM IINumerical schemes in the WWM II• Numerical methods for the sub-problems

– Geographical space• Galerkin schemes (non-monotone, conservative, implicit)

• Residual distribution schemes (monotone, conservative, higher order, explicit/implicit – parallelization of implicit scheme underway)

– Source term integration • Semi-implicit (WAM) or (SWAN)

• Dynamical (WWIII)

• Runge-Kutta

– Spectral space• Ultimate Quickest (explicit, 3rd order in space and time)

• Crank-Nicholson (implicit, 2nd order in space and time)

• Runge-Kutta WENO (explicit, 5th order in space, 3rd order in time)

• WWM fully coupled to SELFE– Callable as a routine – Use same sub-grid – efficiency

• Radiation stress formulations– Longuet-Higgins and Stewart (2D)– Xia (2004), Mellor (2003), Ardhuin (in progress)

• Benchmarks– L31, L51, analytical, hurricane Isabel (2003)….

ONR testbed: L31

x (m)

Set up (m)

Time (hours)

ONR testbed: L51

Nicholson test

STC model (Nicholson et al. 1997)