Global Patterns of Turbulence and Diapycnal Mixing from CTD-Chipods on the Global Repeat Hydrography Program

With an aim to quantify global patterns of ocean mixing, we have developed the CTD-chipod, an instrument that measures the turbulent dissipation rate of temperature variance from standard shipboard CTD. First, turbulent diffusivities and turbulent dissipation rate inferred from the CTD-chipod are compared to that from traditional turbulence profilers with shear probes, suggesting the method does not suffer from significant bias. CTD-chipods have now been deployed on several of the global repeat hydrography program cruises, including the complete P16 line from 60S to 55N in the Pacific. Here we discuss broad patterns of mixing from these observations, as well as focusing on some specific interesting features. In particular, a section of higher resolution sampling across the equator from 5S to 5N in the Pacific suggests elevated abyssal mixing in that region. This and other patterns will be examined in relation to large-scale patterns of stratification, velocity, and shear. The observations will also be compared to other common parameterizations of mixing from shear and strain. These chipod measurements are a step towards constraining the spatial and temporal patterns of turbulent mixing across the world’s oceans, in order to better understand dissipative mechanisms and their role in ocean dynamics.