The information is stored temporarily onboard the wave buoy and then transferred to a computer back at the shore by a radio signal. Information on wave height, timing and direction is then placed on this website.
Coastal scientists use this information to monitor the type and variability of wave conditions, which helps short-term and long-term investigations of natural coastal processes including accretion and erosion. Maritime organisations use wave data to plan port activities and to support navigational information.
The buoy measures vertical acceleration by means of an accelerometer. The accelerometer is mounted on a gravity-stabilised platform that is suspended in a fluid-filled plastic sphere. The sphere is located at the base of the buoy. This data is then processed to give vertical displacement (wave height).
The buoy measures horizontal acceleration using 2 accelerometers and an onboard compass to give the directional displacement in 2 horizontal axes. With this information, the north-south and east-west directions are calculated. The water level and directional data are then transmitted to the shore station as a high-frequency radio signal.
The Canterbury Wave Buoy is calibrated every 12 months. During calibration and maintenance checks the wave buoy is, of course, removed from the ocean and taken to Christchurch. Calibration is performed by NIWA scientists using a buoy calibrator to simulate sinusoidal waves.
The wheels are electrically controlled and the frequency can be varied from 0.016 - 0.25 Hz. It is usual to check 3 frequencies during a calibration. During the calibration procedure, the following characteristics of the buoy are also checked:
For more technical information about wave monitoring, check out the Manly Hydraulics Laboratory in Australia.
The wave buoy is moored in approximately 76 metres of water, 17 kilometres east of Le Bons Bay, Banks Peninsula at Latitude 43° 45' South, Longitude 173° 20' East. We chose this location and depth of water, so that the characteristics of the measured waves are not modified by any landmass or by the seabed.
You can download information on significant wave height, mean wave timing and wave direction. This information is updated daily at 05:35, 11:35, 17:35 and 23:35.
(03) 353 9007
0800 324 636 (EC INFO)
More contact details »