2:15 PM - 2:30 PM
[AOS11-15] High-resolution temperature sensors: a decade of internal wave turbulence observations
Keywords:high-resolution temperature sensors, internal wave turbulence observations
Under conditions of tight temperature-density relationship, the temperature data are used to quantify turbulent overturns. These observations show two distinctive turbulence processes that are associated with different phases of a large-scale, mainly tidal, internal gravity wave: i) highly nonlinear turbulent bores during the upslope propagating phase, and ii) Kelvin-Helmholtz billows, at some distance above the slope, during the downslope phase. While the former may be associated in part with convective turbulent overturning following Rayleigh-Taylor instabilities, the latter are mainly related to shear-induced instabilities. Under weaker stratified conditions, away from boundaries, free convective mixing appears more often, but a clear inertial subrange in temperature spectra is indicative of dominant shear-induced turbulence. With stratification, turbulence is seen to increase in dissipation rate and diffusivity all the way to the bottom, which challenges the idea of a homogeneous bottom boundary layer.