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Chapter 2. The kinematic part of the energy balance equation
Chapter 3. Parametrization of source terms and the energy balance in a growing wind sea
Chapter 4. An optimal interpolation scheme for assimilating altimeter data into the WAM model
Chapter 5 Numerical scheme
Chapter 6 The WAM-model software
Chapter 7 Wind-wave interaction at ECMWF
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6.4 Processing programs
There are two processing programs, namely
| 1) CHIEF, |
| 2) BOUINT. |
The program BOUINT is used for nested grids. It interpolates, in time and space, the output spectra from a coarse grid model run onto the fine grid along the boundaries of the coarse and fine grids.
CHIEF is the shell program of the stand-alone version of the wave model which calls the subroutine version WAVEMDL of the wave model. All time-dependent variables and user defined parameters are set, the wind fields are transformed to the wave model grid and the transport equation is integrated over a chosen period. The program uses the output files of PREPROC as set-up files and the files generated by PRESET or a previous model run as initial values. A wind input file has to be provided by the user. All additional information must be defined in the user input file. The model can be integrated with independently chosen propagation, source term and wind time steps, under the restriction that all time step ratios must be an integer, or the inverse of an integer.
A number of model options and parameters may be selected by the user in the program input. The following model options are implemented:
| 1) Cartesian or spherical propagation, |
| 2) deep or shallow water, |
| 3) with or without depth refraction or with depth and current refraction, |
| 4) nested grids, |
| 5) time interpolation of winds, or no time interpolation, |
| 6) model output at regular intervals, or through a list, |
| 7) printer and/or file output of selected parameters. |
All run-time-dependent files are fetched dynamically and follow a fixed file name convention. The user has control over directory names and paths through the model input. If selected, model results are saved in four files. These files contain:
| 1) gridded output fields of significant wave height, mean wave direction, mean frequency, friction velocity, wave direction, peak frequency, drag coefficient and normalized wave-induced stress, |
| 2) gridded output field of swell parameters such as wave height, swell direction, mean wind-wave direction and mean swell frequency, |
| 3) spectra at selected grid points, |
| 4) swell spectra at selected grid points. |
A comprehensive view of the program CHIEF, which is clearly the most important part of the model system, is given in the flow chart of Fig. 6.3 . We need not discuss details here and only highlight the main points. The subroutine INITMDL is only called once. It reads the necessary input generated by PREPROC and PRESET (or by a previous model run) and sets up the necessary information for the model run. PREWIND deals with reading of the winds provided by the user and the transformation to the wave model grid. If required, time interpolation is performed. Furthermore, the subroutine WAMODEL integrates the energy balance equation. The physics of the wave model is contained in the subroutines PROPAGS and IMPLSCH which are called in a loop over the blocks of the wave model grid. PROPAGS deals with propagation and refraction, whereas IMPLSCH performs the implicit integration in time of the source terms
(SINPUT), 
(SNONLIN), 
(SDISSIP) and 
(SBOTTOM). The
remaining subroutines in WAMODEL are related to the generation of output
files or restart files. Finally, the subroutine WAMASSI assimilates altimeter
wave-height data according the optimum interpolation (OI) method described
in Chapter 4. The quality control
and the correction of the data is performed by the subroutine GRFIELD while
the increments according to OI method are determined in OIFIELD use the
subroutine ANALYSE. Using scaling laws of swell and wind-wave generation
the wave spectra and the surface winds are updated in UPDATE.Next Section
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23.04.2002 |
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