Sofar SPOTTER - Spotter Measurements; Waves:Standard Mode; Waves:Partition Mode; Waves:Spectrum Mode

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SPOTTER
Currently Spotter has two primary run modes available: Waves mode and
Track mode. These two run modes can be accessed remotely through the
online Dashboard. Waves:Standard is the default mode and will likely be the
mode that is used most of the time. Waves mode can be further customized
by choosing Waves:Spectrum or Waves:Partition based on your needs. In
Track mode, the system will provide faster position updates (e.g. for retrieval),
but no wave data.
Waves:Standard mode
Recommended for standard marine monitoring applications. In the standard
Waves mode, Spotter collects wave displacement data continuously at 2.5Hz.
Every half hour, the system computes the complete cross-spectral matrix and
estimates bulk statistics and Spotter geographical location. To save trans-
mission bandwidth, two time-stamped 30-minute updates of bulk statistics
are transmitted every hour. So although the data resolution is 30 minutes, the
satellite updates are hourly.
The Standard Waves message payload consists of:
• Time (epoch)
• Position (latitude and longitude)
• Signicant Wave Height - estimated from zeroth-order moment of wave
spectrum (Hm0)
• Peak Period - period associated with peak of the wave spectrum (Tp)
• Peak Direction - mean direction at peak of spectrum
• Peak Directional Spread - directional spreading at peak of spectrum
• Mean Period - variance-weighted mean period (Tm01)
• Mean Direction - variance-weighted mean direction
• Mean Directional spread - variance-weighted mean directional spread
All bulk statistics are computed over frequency range 0.03 – 0.8Hz.
For denitions of various bulk wave statistics see e.g. Holthuijsen (2007).
Spotter Measurements