Open AccessThe effect of wave‐induced turbulence on the ocean mixed layer during tropical cyclones: Field observations on the Australian North‐West Shelf
Author(s) -
Toffoli A.,
McConochie J.,
Ghantous M.,
Loffredo L.,
Babanin A. V.
Publication year - 2012
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jc007780
Subject(s) - mixed layer , turbulence , breaking wave , geology , tropical cyclone , atmospheric sciences , forcing (mathematics) , surface layer , turbulence kinetic energy , mixing (physics) , storm , turbulent diffusion , geophysics , climatology , meteorology , oceanography , physics , wave propagation , layer (electronics) , materials science , quantum mechanics , composite material
Field observations of water temperature on the Australian North‐West Shelf (Eastern Indian Ocean) with the support of numerical simulations are used to demonstrate that the injection of turbulence generated by the wave orbital motion substantially contributes to the mixing of the upper ocean. Measurements also show that a considerable deepening of the mixed layer occurs during tropical cyclones, when the production of wave‐induced turbulent kinetic energy overcomes the contribution of the current‐generated shear turbulence. Despite a significant contribution to the deepening of the mixed layer, the effect of a background current and atmospheric forcing are not on their own capable of justifying the observed deepening of the mixed layer through most of the water column. Furthermore, variations of a normally shallow mixed layer depth are observed within a relatively short timescale of approximately 10 hours after the intensification of wave activity and vanish soon after the decay of storm surface waves. This rapid development tends also to exclude any significant contribution by wave breaking, as small rates of vertical diffusivity for wave breaking‐induced turbulence would require longer timescales to influence the depth of the mixed layer.