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08:54
Measurements of Waves in a Wind-wave Tank Under Steady and Time-varying Wind Forcing
Published on: February 13, 2018
Internal wave turbulence near a Texel beach
Hans van Haren1, Louis Gostiaux, Martin Laan
1Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands. hans.van.haren@nioz.nl
Plos One
|March 10, 2012
Summary
Beachgoers may feel surprising temperature changes in the sea due to internal waves and turbulence. These underwater motions, common in the deep ocean, were unexpectedly detected near a shallow Dutch coast.
Area of Science:
- Oceanography
- Fluid Dynamics
- Coastal Processes
Background:
- Swimmers often experience rapid temperature fluctuations in coastal waters.
- These variations are typically attributed to surface phenomena, not internal water movements.
Purpose of the Study:
- To investigate the cause of observed temperature variations near a beach.
- To quantify the characteristics and mixing effects of internal waves in a shallow coastal environment.
Main Methods:
- Deployment of high-precision sensors near Texel Island, Netherlands.
- Measurement of fast temperature changes and water stratification.
- Analysis of internal waves, fronts, and turbulence.
Main Results:
- Fast temperature changes up to 1°C were recorded, indicating internal waves and turbulence.
- Internal beach-waves exhibited amplitudes ten times larger than surface wind waves.
- Turbulent mixing diffusivity estimates ranged from 10(-4)-10(-3) m(2) s(-1).
Conclusions:
- Internal waves and turbulence significantly impact temperature distribution in shallow seas.
- Observed mixing is higher than in the open ocean but lower than wave breaking over deep slopes.
- These findings challenge the assumption of complete homogenization in shallow coastal waters.
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