Numerical Developments of the WAVEWATCH III Model
The Consumer Option for an Alternative System to Allocate Losses (COASTAL) Act requires an accurate modeling of flooding due to hurricanes. The wave model chosen as part of developing this modeling system is the WAVEWATCH III wave model.
WAVEWATCH III (https://github.com/noaa-emc/ww3) is a community wave modeling framework that includes the latest scientific advancements in the field of wind-wave modeling and dynamics. The core of the framework consists of the WAVEWATCH III third-generation wave model (WAVE-height, WATer depth and Current Hindcasting), developed at NOAA/NCEP.
WAVEWATCH III solves the random phase spectral action density balance equation for wavenumber-direction spectra. The implicit assumption of this equation is that properties of medium (water depth and current) as well as the wave field itself vary on time and space scales that are much larger than the variation scales of a single wave. The model includes options for shallow-water (surf zone) applications, as well as wetting and drying of grid points. The wave model is a sophisticated modeling system with numerous developments that have been added in recent years (wave – hurricane interaction physics, new wave growth and dissipation physics packages, wave – mud, wave – vegetation and wave – bottom interaction physics to name a few) that make this model attractive for this project. Propagation of a wave spectrum can be solved using regular (rectilinear or curvilinear) and unstructured (triangular) grids. With this project and in collaboration with USACE, a major update in parallelization and solver scheme has led to a significant enhancement in the model performance on modern high-performance computing architectures (Fig 1). This improvement makes it possible to carry out wave simulations in very high resolution domains with extensive computational grids – a necessary condition for accurate simulations of total inundation (Fig 2). In addition, the code is extended to include the software that interfaces with the Earth System Modeling Framework (ESMF) allowing the model to be used in community modeling systems. As a result of this new feature, the WAVEWATCH III is coupled with the ADCIRC model for wave-surge modeling for the coastal applications (Fig 3). In addition, the code will be implemented operationally in coupled systems at NCEP, for the deterministic Global Forecast System (GFSv16) and the Global Ensemble Forecast System (GEFSv12).
Fig. 1 - Schematic view of different parallelization approaches implemented in WW3 for structured and unstructured grids.
(See Abdolali et al 2020 for more details)
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Fig 2 - Model performance (v6.07) on HPC environment and Scalability of WW3 models for different parallelization algorithms and explicit/implicit numerical solvers
(See Abdolali et al 2020 for more details).
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The latest release of WAVEWATCH III v6.07 is available on GitHub (https://github.com/NOAA-emc/WW3) by the WAVEWATCH III development group [WW3DG, 2019]. With this release, WAVEWATCH III has moved to open-development on GitHub to facilitate increased engagement with the wave modeling community. Being a community model with a very active international team of wave developers also allows us to partner and leverage resources. The WAVEWATCH III Development Group is made up of 50+ scientists and programmers spanning most continents, with many more joining us with contributions for further development of the model. Development has now fully matured as a community driven effort, with code management led by NCEP scientists.
Fig 3 - Frequency spectrum at five selected gauges comparing observation (a) versus WW3 simulations during Hurricane Ike 2008 (See Abdolali et al 2020 for more details).
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All model configurations and results are pre-decisional and for official use only.
The WAVEWATCH III® Development Group (WW3DG), 2019: User manual and system documentation of WAVEWATCH III® version 6.07. Tech. Note 333, NOAA/NWS/NCEP/MMAB, College Park, MD, USA, 326 pp. + Appendices.
Abdolali A., Roland, A., Van Der Westhuysen, A., Meixner, J., Chawla, A., Hesser, T., Smith, J.M. and M. Dutour Sikiric (2020), Large-scale Hurricane Modeling Using Domain Decomposition Parallelization and Implicit Scheme Implemented in WAVEWATCH III Wave Model, Coastal Engineering, 157, 103656, https://doi.org/10.1016/j.coastaleng.2020.10365
Abdolali, A., van der Westhuysen, A., Ma, Z. Mehra, A., Roland, A. and Moghimi, S. Evaluating the accuracy and uncertainty of atmospheric and wave model hindcasts during severe events using model ensembles. Ocean Dynamics (2021). https://doi.
