Model Description

WAVEWATCH III (Tolman 1997, 1999a) is a third generation wave model developed at NOAA/NCEP in the spirit of the WAM model (WAMDIG 1988, Komen et al. 1994). It is a further development of the model WAVEWATCH I, as developed at Delft University of Technology (Tolman 1989, 1991) and WAVEWATCH II, developed at NASA, Goddard Space Flight Center (e.g., Tolman 1992). WAVEWATCH III, however, differs from its predecessors in many important points such as the governing equations, the model structure, the numerical methods and the physical parameterizations.

WAVEWATCH III solves the 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. A further constraint is that the parameterizations of physical processes included in the model do not address conditions where the waves are strongly depth-limited. These two basic assumptions imply that the model can generally by applied on spatial scales (grid increments) larger than 1 to 10 km, and outside the surf zone.

A presentation on the features and improvements in the new multigrid version of WAVEWATCH III is available here (and also as a PDF).

The NOAA Technical Implementation Notice 07-51 has the details regarding the changes to WAVEWATCH III implemented as of September 18, 2007.

Model Features

Physical features:

• The governing equations of WAVEWATCH III include refraction and straining of the wave field due to temporal and spatial variations of the mean water depth and of the mean current (tides, surges etc.), when applicable.
• Parameterizations of physical processes (source terms) include wave growth and decay due to the actions of wind, nonlinear resonant interactions, dissipation (`whitecapping') and bottom friction.
• Wave propagation is considered to be linear. Relevant nonlinear effects such as resonant interactions are, therefore, included in the source terms (physics).
• The model includes several alleviation methods for the Garden Sprinkler Effect (Booij and Holthuijsen, 1987, Tolman, 2002c).
• The model includes sub-grid representation of unresolved islands (Tolman 2002e).
• The model includes options for chosing two source term packages: the first is based on cycles 1 through 3 of the WAM model (WAMDIG 1988); the second is based on Tolman and Chalikov (1996). The source term packages are selected at the compile level.
• For research purposes only, the model includes a full nonlinear interaction source term option.
• The model includes dynamically updated ice coverage.
• The model is prepared for data assimilation, but no data assimilation package is provided.

Numerical features:

• The model is written in ANSI standard FORTRAN 90, fully modular and fully allocatable.
• The model uses a regularly spaced longitude-latitude grid (longitude and latitude increment do not need to be equal)i and, optionally, a Cartesian grid.
• Wave energy spectra are discretized using a constant directional increment (covering all directions), and a spatially varying wavenumber grid. The latter grid corresponds to an invariant logarithmic intrinsic frequency grid (Tolman and Booij 1998).
• Both a first order accurate and third order accurate numerical scheme are available to describe wave propagation (Tolman 1995). The propagation scheme is selected at the compile level.
• The source terms are integrated in time using a dynamically adjusted time stepping algorithm, which concentrates computational efforts in conditions with rapid spectral changes (Tolman 1992, 1997, 1999a).
• The model can optionally be compiled to include shared memory parallelisms using OpenMP compiler directives.
• The model can optionally be compiled for a distributed memory environment using the Message Passing Interface (MPI, see Tolman 2002a).

Output options:

• Gridded fields of 18 input and mean wave parameters such as the significant wave height, directions, frequencies etc.
• Output of wave spectra at selected locations.
• Output of wave spectra along arbitrary tracks.
• Up to 9 restart files per model run.
• Files with boundary data for up to 9 separate nested runs.
• The model provides binary or ASCII output, as well as output for the GrADS graphics package by means of post processing.

Documentation and Source Code

The documentation of WAVEWATCH-III is available on line in pdf files. For each released model version an errata page is maintained, which is the sole source of distributing errors and fixes of the model. To receive information on model changes etc, subscribe to the MMAB mailing list.

Model version 1.15:

• Tolman , H. L, 1997: User manual and system documentation of WAVEWATCH-III version 1.15. NOAA / NWS / NCEP / OMB Technical Note 151, 97 pp. (0.74MB PDF file)

Model version 1.18:

• Tolman , H. L, 1999a: User manual and system documentation of WAVEWATCH-III version 1.18. NOAA / NWS / NCEP / OMB Technical Note 166 , 110 pp. (0.76MB PDF file).
• Tolman , H. L, 1999b: WAVEWATCH-III version 1.18: Generating GRIB files. NOAA / NWS / NCEP / OMB Technical Note 167, 7 pp. (0.15MB PDF file)
• Tolman , H. L, 1999c: WAVEWATCH-III version 1.18: Post-processing using NCAR graphics. NOAA / NWS / NCEP / OMB Technical Note 168, 9 pp. (0.15MB PDF file)
• Version 1.18, errata, problems and fixes.

Model version 2.22 :

• Tolman, 2002g: User manual and system documentation of WAVEWATCH-III version 2.22. NOAA / NWS / NCEP / MMAB Technical Note 222, 133 pp. (0.89MB PDF file).
• Version 2.22, errata, problems and fixes.

Source Code Distribution

Model versions 1.18 and 2.22 have been distributed as public domain software,and can be found at the previous WAVEWATCH source code ftp site.

Model versions 3.14 through 5.16, were distributed under an open source style license through a password protected distribution site.

Starting with model version 6.07, WAVEWATCH III^® is released on GitHub.

The WAVEWATCH III^® project page is here.

The latest release (currently at 6.07) is available as a compressed tarball or zipfile from the project page.

To help users and developers navigate the new repositories, we have created two sets of guidelines in GitHub to help you navigate our community modeling framework, one for users and the other for developers:

• If you are a user and would like to access the code for applications and do not plan to engage in development work, see the User Guide.


• If you are a developer and would like to add a new feature to the code, see the Developer Guide.

The WW3 GitHub wiki hosts a description of the model, its main features, output options, user and developer guides, technical documentation and latest news.

Model development

The model is subject to continuous development. The following new features are presently being incorporated in WAVEWATCH III at NCEP, or are considered for incorporation in the future.

• An alternative vector description of stresses has been included in the present development version of WAVEWATCH III.
• Alternative source terms will be considered. We are particularly concentrating efforts on surf-zone phsysics and new nonlinear interaction source terms.
• A multi grid or mosaic wave model version is nearing completion. In the model version, an arbitrary number of grids will be considered simultaneously, as well as all relevant interactions between grids.
• As a precursor to this, a moving grid option has been developed particularly for hurricane wave research.

New releases will generally become available after implementation of new model version at NCEP. Tentatively, a new model implementation and a subsequent model release is scheduled for the fall of 2006.

References

Booij, N. and L. H. Holthuijsen, 1987: Propagation of ocean waves in discrete spectral wave models. J. Comp. Phys., 68, 307-326.

Komen, G. J., L. Cavaleri, M. Donelan, K. Hasselmann, S. Hasselmann and P. A. E. M. Janssen, 1994: Dynamics and Modelling of Ocean Waves. Cambridge University Press, 532 pp.

Tolman, H. L., 1989: The numerical model WAVEWATCH: a third generation model for the hindcasting of wind waves on tides in shelf seas. Communications on Hydraulic and Geotechnical Engineering, Delft Univ. of Techn., ISSN 0169-6548, Rep. no. 89-2, 72 pp.

Tolman, H. L., 1991: A third-generation model for wind waves on slowly varying, unsteady and inhomogeneous depths and currents. J. Phys. Oceanogr. , 21, 782-797

Tolman, H. L., 1992: Effects of numerics on the physics in a third-generation wind-wave model. J. Phys. Oceanogr., 22, 1095-1111.

Tolman, H. L., 1995: On the selection of propagation schemes for a spectral wind wave model. NWS/NCEP Office Note 411, 30 pp. + figures.

Tolman, H. L., 1997: User manual and system documentation of WAVEWATCH-III version 1.15. NOAA / NWS / NCEP / OMB Technical Note 151, 97 pp. (0.74MB PDF file).

Tolman, H. L., 1999a: User manual and system documentation of WAVEWATCH-III version 1.18. NOAA / NWS / NCEP / OMB Technical Note 166, 110 pp. (0.76Mb pdf file).

Tolman, H. L., 1999b: WAVEWATCH-III version 1.18: Generating GRIB files. NOAA / NWS / NCEP / OMB Technical Note 167, 7 pp. (0.15MB pdf file)

Tolman, H. L., 1999c: WAVEWATCH-III version 1.18: Post-processing using NCAR graphics. NOAA / NWS / NCEP / OMB Technical Note 168, 9 pp. (0.15Mb pdf file).

Tolman, H. L., 2001: Improving propagation in ocean wave models. Ocean Wave Measurement and Analysis, San Francisco, CA, B. L. Edge and J. M. Hemsley, Eds., ASCE, 507-516.

Tolman, H. L., 2002a: Distributed memory concepts in the wave model WAVEWATCH III. Parallel Computing, 28, 35-52.

Tolman, H. L., 2002b: Validation of WAVEWATCH III version 1.15 for a global domain. NOAA / NWS / NCEP / OMB Technical Note Nr. 213, 33 pp. (2.7Mb pdf file).

Tolman, H. L., 2002c: Alleviating the Garden Sprinkler Effect in wind wave models. Ocean Modelling, 4, 269-289.

Tolman, H.L. 2002d: Limiters in third-generation wind wave models. Global Atmosphere and Ocean. System, 8, 67-83.

Tolman, H. L., 2002f: Testing of WAVEWATCH III version 2.22 in NCEP's NWW3 ocean wave model suite. NOAA / NWS / NCEP / OMB Technical Note Nr. 214, 99 pp. (13 Mb pdf file in color or gresyscales).

Tolman, H. L., 2002g: User manual and system documentation of WAVEWATCH-III version 2.22. NOAA / NWS / NCEP / MMAB Technical Note 222, 133 pp. (0.89Mb pdf file).

Tolman, H. L., 2003: Treatment of unresolved islands and ice in wind wave models. Ocean Modelling, 5, 219-231.

Tolman, H. L., B. Balasubramaniyan, L. D. Burroughs, D. V. Chalikov, Y. Y. Chao, H. S. Chen, and V. M. Gerald, 2002: Development and implementation of wind generated ocean surface wave models at NCEP. Weather and Forecasting, 17, 311-333.

Tolman, H. L., and N. Booij, 1998: Modeling wind waves using wavenumber-direction spectra and a variable wavenumber grid. The Global Atmosphere and Ocean System, 6, 295-309.

Tolman, H. L. and D. Chalikov, 1996: Source terms in a third-generation wind-wave model. J. Phys. Oceanogr, 26, 2497-2518.

WAMDIG 1988: The WAM model - A third generation ocean wave prediction model. Journal of Physical Oceanography, 18, 1775-1810.