This software package has been created for generating grids for WAVEWATCH III using MATLAB. This package has been developed and tested on MATLAB v7 or higher.

Documentation : Documentation is available at three levels. First, is the grid generation manual -- grid_generation.pdf -- that is included with the release of the software (download the images from ftp to compile tex: wget ftp://polar.ncep.noaa.gov/tempor/ww3ftp/gridgen.images.tar.gz). The second, are the comments in the master scripts that explain what the individual parts of the code are doing. And finally, there are brief explainations in each subroutine that can be read from the MATLAB workspace by typing help , where is the subroutine. (NOTE: The path to the subroutines should be set when trying this option).

Installation : To install the gridgen to your local system, including all the required binary files, run on your Matlab console: cd gridgen setup_gridgen

            It will take some time, depending on your internet connection, but the gridgen will
            be added to your local path and the binary files will be downloaded automatically.

GIT users : If for any reason you want to avoid the "Installation" steps above, follow the instructions below. If you are a developer and/or acquired this package through NCEP's git repository, you will need to download the binary files package gridgen.tgz. Large binary files are not available in the GIT repository, and need to be added to your griden local copy reference_data directory. After you cd to reference_data, get the binaries using:

            wget ftp://polar.ncep.noaa.gov/tempor/ww3ftp/gridgen_addit.tgz

            This will unpack the netcdf batymetry files:
              - etopo1.nc 
              - etopo2.nc 
            and matlab binary files:
              - coastal_bound_coarse.mat
              - coastal_bound_high.mat   
              - coastal_bound_low.mat
              - coastal_bound_full.mat    
              - coastal_bound_inter.mat  
              - optional_coastal_polygons.mat

.

Dependency : Matlab and netcdf routines for matlab. Netcdf toolbox for Matlab can be obtained from (http://mexcdf.sourceforge.net/) (NOTE: Netcdf toolbox is only used for reading the global bathymetry data files If you have your own independent set of routines for reading netcdf files then only a few lines need to be changed in the 'generate_grid.m' routine. These lines have been marked)

Files : There are 3 sub-directories bin/ -- this stores all the scripts used in the grid generation routine examples/ -- this stores 2 examples of master scripts that call the different subroutines for creating grids. An example for a regional grid and a global grid (which has some differences) have been shown, as well as a script that is used to modify the traditional land - sea mask for WAVE WATCH III to one for the multi-grid version (version 3.10 and higher). This is done for the regional grid assuming that it would be nested with the global grid in the multi-grid version reference_data/ -- this stores all the reference data that is needed for creating grids and includes two global grids, GSHHS shoreline polygon database and an optional user defined polygon database (combined with a flag file that determines which of these polygons are to be used) for masking out water bodies that do not play a critical role in wave propagation

Addendums : 1. The generate_grid function now has two extra parameters that need to be set before the call can be made -- a cut-off depth and a representative depth for dry cells.

2. Matlab now has built in support for NETCDF and those have been incorporated in the generate_grid.m routine
3. A series of bugs were cleaned up. These are a) Getting rid of spurious NaN values in generate_grid b) Changing the algorithm in compute_boundary to remove errors associated with improper closing of certain boundaries c) Speed up in the clean_mask routine d) Generating grids only in the 0 - 360 lon range (this is the range in which the boundaries are defined, and switching to -180 - 180 range was leading to improper treatment of boundary closure in certain cases.

IMPORTANT : Gridgen now does not require the grids to be rectilinear to allow for development support for curvilinear grids. Thus lat / lon arrays are now 2 dimensional to allow for varying resololution. Gridgen will not make the arrays needed for the grids. There are number of softwares available for that, but given the grids will generate all other features -- bathymetry, masks and obstruction grids. See examples for how to generate the 2D grids for rectilinear (constant spacing lat/lon) domains

Last updated : 21/03/2021

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