Wind-wave coupled downward-bursting boundary layer (DBBL) beneath the sea surface

By synthesizing data of the turbulent structure beneath wind waves in laboratory tanks, with some re-analyses, we propose the existence of a particular turbulent boundary layer which is directly coupled with wind waves, a "downward-bursting boundary layer (DBBL)" in water beneath wind waves. The data set indicates that the depth of this layer is from 3 to 7, or about 5 times the significant wave height of wind waves. The data observed in laboratory tanks agree with data of acoustic observations of bubble clouds under breaking wind waves in the sea made by Thorpe (1986, 1992). It is inferred that DBBL is formed in equilibrium with the local wind waves, as a common feature from initially generated wind waves, young laboratory wind waves to mature wind waves in the sea.