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See recent photos from NDBC weather buoy 42039 in the Gulf of Mexico.
Real Time Raw Spectral Wave Information
Date/Time Format (YYYY MM DD hh)
The date/time is of the form, 'YYYY MM DD hh', which represents the year, month, day and hour of the measurement in GMT. GMT is Greenwich Mean Time and is five hours ahead of Eastern Standard Time. For Daylight Savings Time, the difference is one hour less. In other words, 12 GMT is 7 AM EST (8 AM EDT). For West Coast mariners, Pacific Standard Time = GMT - 8 hours.
This is the approximate frequency which separates the long wavelength waves (swell, which typically have been generated at a remote location) and the shorter wavelength waves (wind waves generated locally). This is a gross approximation which attempts to provide a better idea of the sea state and allows the estimation of the "steepness" of the waves.
Spectral Wave Density (Frequency)...
Energy in (meter*meter)/Hz, for each Frequency (typically from 0.03 Hz to 0.40 Hz, but may vary with some stations). Repeats until the end of the recorded spectrum is reached.
For more information on the mathematics behind the measuring of surface water waves, see the waves help section.