Microscale, finescale, and mesoscale measurements made during the 2004 Structured Mixing Project (Micro-Tow 04) Cruise

Abstract

A physical oceanographic sampling voyage was made with RV Endeavor during August 2004 to evaluate diapycnal mixing processes on the continental shelf south of Massachusetts and Rhode Island, USA. The goal of the project was to look for a relationship between intensity of microstructure (thermal variance dissipation rate) and finestructure (background temperature gradient), in so-called doubly-stable water, which would be indicative of a density gradientdependent diapycnal heat flux. To satisfy the requirement that a large amount of data be collected to constrain the statistically estimated result, a microstructure sensor was towed on a platform behind the ship, providing continuous sampling at the depths of interest. To obtain the necessary finestructure quantities the platform measured temperature, conductivity and depth with a standard pumped Seabird 9plus CTD. Attitude and speed of the platform were recorded to assure proper data quality.This report shows temperature, salinity, density, and sound speed in twenty-five tow-yo transects obtained using the towed unit. Only statistics and results from microscale data are shown. In waters with stable salt stratification and stable temperature stratification, a previously obtained empirical result of reduced flux at increased density gradient is supported by the data.

Modeling and Forecasting Ocean Acoustic Conditions

“…However, making improvements to acoustic system performance prediction poses a strong challenge to ocean modeling capabilities. The reasons include incomplete dynamics in models (such as the absence of explicit, double-diffusive influences on intrusions known to affect sound (Colosi et al 2012a;Duda and Sellers 2016)), insufficient resolution of the dynamical models, and insufficient data to constrain data-driven models in the absence of special regional focus. Data-constrained modeling is now routine (Edwards et al 2015).…”