CDIP Wave Measurement Stations

The Coastal Data Information Program (CDIP) uses a variety of instruments to collect wave data. Waves are measured offshore in deep water using buoys or pressure sensors attached to oil drilling platforms. This includes nondirectional buoys which measure wave energy and, increasingly, directional buoys which also measure some basic directional properties of the wave field such as mean wave direction and directional spread, as a function of wave frequency or period.

Close to shore, in water depths of 30 to 60 feet, waves are measured using pressure sensors mounted near the bottom. These instruments measure pressure fluctuations, or the changing height of the water column, associated with passing waves. These pressure time series can be converted to sea surface elevations and wave frequency spectra. Arrays of four pressure sensors placed in a 6m square configuration provide directional information similar to that acquired by directional buoys.

In addition to wave data, wind and temperature data are collected at some sites. Sea temperature is measured either by buoys or by temperature gauges mounted to a pier. Anemometers are used to collect wind data, which can be converted to average and maximum velocity.

Frequently asked questions

What do Hs, Tp and Dp stand for?

  • Hs = Significant wave height of swell, or roughly the average height of the 1/3rd highest waves (in meters and feet);
  • Tp = Peak period of the swell (in seconds);
  • Dp = Compass direction from which the waves are arriving (in degrees), e.g. 180 = fr om the south, 270 = from the west.