Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 Introduction
- 2 Observation techniques
- 3 Description of ocean waves
- 4 Statistics
- 5 Linear wave theory (oceanic waters)
- 6 Waves in oceanic waters
- 7 Linear wave theory (coastal waters)
- 8 Waves in coastal waters
- 9 The SWAN wave model
- Appendix A Random variables
- Appendix B Linear wave theory
- Appendix C Spectral analysis
- Appendix D Tides and currents
- Appendix E Shallow-water equations
- References
- Index
2 - Observation techniques
Published online by Cambridge University Press: 03 February 2010
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 Introduction
- 2 Observation techniques
- 3 Description of ocean waves
- 4 Statistics
- 5 Linear wave theory (oceanic waters)
- 6 Waves in oceanic waters
- 7 Linear wave theory (coastal waters)
- 8 Waves in coastal waters
- 9 The SWAN wave model
- Appendix A Random variables
- Appendix B Linear wave theory
- Appendix C Spectral analysis
- Appendix D Tides and currents
- Appendix E Shallow-water equations
- References
- Index
Summary
Key concepts
Visual observations are often the only source of wave information available to the engineer. Sometimes measurements made with instruments are available.
Measurement techniques can be divided into in situ techniques (instruments deployed in the water) and remote-sensing techniques (instruments deployed at some distance above the water).
The most common in situ instruments are wave buoys and wave poles. Other in situ instruments are inverted echo-sounders, pressure transducers and current meters. These instruments need to be mounted on some structure at sea.
The most common remote-sensing technique is radar, which is based on actively irradiating the sea surface with electro-magnetic energy and detecting the corresponding reflection. Radar may be deployed from the coast (e.g., with a receiving station in the dunes), from fixed platforms (e.g., oil-production platforms) or from moving platforms at relatively low altitude (airplanes) or high altitude (satellites).
Radar can be used to obtain images of the sea surface, but it can also be used as a distance meter or as a surface-roughness meter.
Each measurement technique has its own peculiarities as regards operational performance, accuracy, maintenance, cost and reliability.
The most common result of a wave measurement is a time record of the sea-surface elevation at a fixed (horizontal) location.
Introduction
Waves are not only observed by surfers, swimmers or tourists from the beach. Experienced crew members onboard voluntary observing ships (VOS; or voluntary observing fleet, VOF), too, observe the waves and report wave height, period and direction daily to meteorological institutions around the world. Scientists and engineers too are watching waves.
- Type
- Chapter
- Information
- Waves in Oceanic and Coastal Waters , pp. 10 - 23Publisher: Cambridge University PressPrint publication year: 2007