The Relationship between the Thorpe and Ozmidov Length Scales from Direct Numerical Simulations of Multi-Scale Interactions

The relationship between the Thorpe scale (a measure of length scales of turbulent overturning events) and the Ozmidov scale (which separates the buoyancy subrange from the inertial subrange) will be examined in detail in this study utilizing state-of-the-art direct numerical simulations (DNS) of multi-scale interactions (using the triple code written by Joseph Werne at NorthWest Research Associates). Such a study may have significant and practical implications for deriving global climatology of important atmospheric turbulence parameters such as energy dissipation rates from routine high vertical resolution radiosonde data as proposed by Clayson and Kantha (2008). We will use the DNS results to assess the accuracy and universality of expressions relating the two length scales as suggested in previous field measurements and simulation results. We will evaluate the time evolution of the ratio of the two length scales for the entire computational domain containing multiple instability events and for individual events in subsets of the full domain. In addition, we will explore the dependence of the ratio on various flow parameters, especially the Reynolds number.