CMS-Wave Spectra File

There are several instances where spectral energy files are used. They all use a similar format, shown below.

30 35
0.040 0.050 0.060 0.070 0.080 0.090 0.100 0.110
0.120 0.130 0.140 0.150 0.160 0.170 0.180 0.190
0.200 0.210 0.220 0.230 0.240 0.250 0.260 0.270
0.280 0.290 0.300 0.310 0.320 0.330
200801010000  5.00  10.00  0.130  0.500
0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.02000 0.13000 0.25000
... 

The first line contains:

• The number of frequency bins (30 in this example)
• The number of direction bins (35)

The next set of lines contain frequency values for the grid starting from the smallest and working to the largest frequency. In this example, there are 30 total values starting at 0.040 and incrementing by 0.01 to the largest value of 0.330.

The remaining set of lines are a number of records each containing a line with some information for each record followed by several lines of energy density values for each cell in the spectral grid (in this case 30x35 cells)

200801010000  5.00  10.00  0.130  0.500
0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
0.00000 0.00000 0.00000 0.02000 0.13000 0.25000
... 

There are either 5 or 8 values in the first line of each record. There will be 5 values for normal spectra and 8 values when the spectra is coming from a nested grid cell.

The first 5 values are:

• Time/index identifier (###, YYYYMMDD, or YYYYMMDDHHSS)
• Wind Speed in $m/sec$ (5.0 m/sec in this example)
• Wind Direction in degrees (10.00 degrees)
• Spectral peak frequency (0.13 Hz)
• Tidal offset (0.5 m)

The last 3 values for nested grids (not shown) are:

• Global coordinate of X position of nesting cell
• Global coordinate of Y position of nesting cell
• Significant wave height

Back to CMS-Wave File Formats