Description: Cruise data collected across three separate cruises MeRMEED-1 (WS16336; 1-7 December 2016), MeRMEED-2 (WS17305; 31 October - 10 November 2017) and MeRMEED-3 (WS18066; 4-16 March 2018). All cruises were aboard the R/V F. G. Walton Smith. Cruise region: 76.5W-77.2W, 26.15N-26.8N. Cruises consisted of zonal tethered vertical microstructure profiler (VMP) and vessel mounted acoustic Doppler current profiler (ADCP) surveys, yielding sections of the turbulent dissipation rate (units: W/kg) and zonal and meridional velocity (units: m/s). The VMP used was the tethered Rockland Scientific International VMP-2000, and the ADCP was a vessel-mounted RDI 75 kHz Ocean Surveyor ADCP configured and run through the University of Hawai'i Data Acquisition System (UHDAS) software suite. The VMP was also mounted with a CTD (conductivity-temperature-depth) sensor package, including SBE-3 and SBE-4 sensors. The CTD data was processed according to the manufacturer specifications, using recommended values for the cell thermal mass coefficients (alpha=0.03 and beta=7.0). Files are named as follows: WSxxxxx_CTD.mat, WSxxxxx_vmp_all.mat and WSxxxxx_os75nb.nc for CTD, VMP and ADCP data respectively. Mooring-based data is from two 75 kHz ADCPs, one upward facing and the other downward facing, mounted at approximately 700 m on the RAPID/MOCHA (Rapid Climate Change / Meridional Overturning Circulation and Heat flux Array) mooring WB1 at 76.8W and 26.5N. This configuration gave full depth meridional and zonal velocity profiles (units: m/s) in a water depth of approximately 1300 m. The data spanned December 2015 to March 2017. The data are binned in 16 m depth bins and are bin averaged into 1 hour time bins. File name: WB1_adcp_UV_1hr.mat.

Description: We contend that ocean turbulent fluxes should be included in the list of Essential Ocean Variables (EOVs) created by the Global Ocean Observing System. This list aims to identify variables that are essential to observe to inform policy and maintain a healthy and resilient ocean. Diapycnal turbulent fluxes quantify the rates of exchange of tracers (such as temperature, salinity, density or nutrients, all of which are already EOVs) across a density layer. Measuring them is necessary to close the tracer concentration budgets of these quantities. Measuring turbulent fluxes of buoyancy (Jb), heat (Jq), salinity (JS) or any other tracer requires either synchronous microscale (a few centimeters) measurements of both the vector velocity and the scalar (e.g., temperature) to produce time series of the highly correlated perturbations of the two variables, or microscale measurements of turbulent dissipation rates of kinetic energy (ϵ) and of thermal/salinity/tracer variance (χ), from which fluxes can be derived. Unlike isopycnal turbulent fluxes, which are dominated by the mesoscale (tens of kilometers), microscale diapycnal fluxes cannot be derived as the product of existing EOVs, but rather require observations at the appropriate scales. The instrumentation, standardization of measurement practices, and data coordination of turbulence observations have advanced greatly in the past decade and are becoming increasingly robust. With more routine measurements, we can begin to unravel the relationships between physical mixing processes and ecosystem health. In addition to laying out the scientific relevance of the turbulent diapycnal fluxes, this review also compiles the current developments steering the community toward such routine measurements, strengthening the case for registering the turbulent diapycnal fluxes as an pilot Essential Ocean Variable.