waves & WWATCH wiki
The WAVEWATCH III (TM) - hereinafter WWATCH - modelling framework was originally developped by Hendrik Tolman for the U.S. National Weather Service (NOAA/NWS/NCEP). WAVEWATCH III is a trade mark of the National Weather Service (NWS). Others have joined the development team, this is the case of SHOM (with particular emphasis on the parameterization of physical processes and wave-current interactions), and the Technical University of Darmstadt (numerical schemes on triangle-based meshes). WWATCH is used for routine wave forecasting in the Previmer project.
The goal of this wiki is to facilitate the exchange of information between the different users and developpers of the code, associated tools - and other models -, but also with the users of the model results. You will find here some basic installation information , and here some information on how to use the model .
The phase-averaged spectral wave models represent the local sea state - at any point at the surface of the ocean and any point in time - by a discretized spectrum - say N - which has 2 dimensions: N(k,θ). Here k and θ are the wavenumber (k=2π/L where L is the wavelength) and θ is the direction of propagation (beware of wave direction conventions). The spectrum gives the distribution of the energy or some closely related quantities across the different components. Because the variance of any wave-induced disturbance can be related to the variance of the sea surface elevation, the spectrum can thus be used to compute many statistical parameters (bottom agitation, surface slopes …).
The tasks performed by the model are:
- the propagation of the wave energy as a function of the wavenumber k, direction θ and medium properties (water depth D, current profile …)
- the integration of the sources and sinks of energy for each spectral component.
Some specific file formats are used for various purposes (data storage, grid definition). here you will find a list and description of these formats .
The IFREMER wave hindcasts cover (part of) the time frame from 1997 to 6 days into the future. Up to September 1st 2010, the results are based on a re-run of the models, while the forecast part is a copy of the Previmer output with a monthly clean re-run of the past month …
The wave models in Previmer combine WWATCH and other codes in order to cover a wide range of scales from the global ocean to the beach. The results can be seen on www.previmer.org/previsions/vagues . The model results are available via OpenDAP (NetCDF files: please make a request by mail email@example.com : this is the proper way to make sure that the data flows are monitored and that you are warned about system changes. Otherwise all parameters are dumped on the Ifremer ftp updated twice a day at 3 AM and 3PM UTC, and with a clean monthly update around day 10 of each month.
Validation tools and results
Altimeter , SAR and buoy data are routinely used to monitor the quality of the model output. Data from dedicated field campaigns are also used. For validation and analysis purposes, various parameters are computed from modelled spectra. The full set of tools is described here . Other useful tools are the NRL testing environment for standard test cases.
The quality of a wave model may be described by a wide range of metrics.
Current work at Ifremer and SHOM is based on NCEP's version 3.14 and associated tools. There are three file directories under version control in https://gforge.ifremer.fr/svn/ww3/ , these are
- The ftn directory for WWATCH https://gforge.ifremer.fr/svn/ww3/ftn/trunk
- the bin directory for WWATCH https://gforge.ifremer.fr/svn/ww3/bin
- a TOOLS directory which contains many preprocessing / postprocessing tools … more here
A version 3.14_Ifremer will be submitted to NCEP's svn server as soon as accounts are set up. The main differences between the “standard” 3.14 and 3.14_Ifremer are:
- WWATCH on triangle-based grids : interface with and inclusion of Aron Roland's (TUD) propagation schemes on triangle-based meshes
- an updated wave breaking term as part of the ST3 switch option (which is now tested to also be able to deal with depth-induced breaking: this is Jean François Filipot's thesis work)
- extra output parameters (surface mean square slope, energy fluxes …)
- direct output to NetCDF files with a ww3_ounf program that can be used instead of ww3_outf
- possibility to use an iceberg mask on top of the usual ice mask
- coastal reflection
Some of this is still under development. See the to do list .
More stuff will be discussed at the 1st NOPP wave meeting in San Francisco
Work in progress
The coupling of WWATCH with 3D ocean circulation models uses a generic coupler based on PALM is under development.
Periodic IOWAGA group meetings
*[http://polar.ncep.noaa.gov/waves/index2.shtml Site NOAA/NWS/NCEP/MMAB]
*[http://www.shom.fr/fr_page/fr_act_oceano/vagues/vagues_f.htm | Site du SHOM]