title: Internal wave turbulence near a Texel beach.
abstract: A summer bather entering a calm sea from the beach may sense alternating warm and cold water. This can be felt when moving forward into the sea ('vertically homogeneous' and 'horizontally different'), but also when standing still between one's feet and body ('vertically different'). On a calm summer-day, an array of high-precision sensors has measured fast temperature-changes up to 1 °C near a Texel-island (NL) beach. The measurements show that sensed variations are in fact internal waves, fronts and turbulence, supported in part by vertical stable stratification in density (temperature). Such motions are common in the deep ocean, but generally not in shallow seas where turbulent mixing is expected strong enough to homogenize. The internal beach-waves have amplitudes ten-times larger than those of the small surface wind waves. Quantifying their turbulent mixing gives diffusivity estimates of 10(-4)-10(-3) m(2) s(-1), which are larger than found in open-ocean but smaller than wave breaking above deep sloping topography.
authors.affiliation: Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands. hans.van.haren@nioz.nl
authors.forename: Hans
authors.initials: H
authors.lastname: van Haren
authors.forename: Louis
authors.initials: L
authors.lastname: Gostiaux
authors.forename: Martin
authors.initials: M
authors.lastname: Laan
authors.forename: Martijn
authors.initials: M
authors.lastname: van Haren
authors.forename: Eva
authors.initials: E
authors.lastname: van Haren
authors.forename: Loes J A
authors.initials: LJ
authors.lastname: Gerringa
mesh_terms: D001272:Atmosphere; D009426:Netherlands; D009792:Oceans and Seas; D012621:Seasons; D013696:Temperature; D013997:Time Factors; D014872:Water Movements