Small Flows with Big Consequences: Wave-, Turbulence- and Shear current-Driven mixing under a water surface

Introduction

The triple interactions of surface waves, turbulence, and shear currents (WTS) in the upper layer of the ocean play a key role in the Earth's climate and ecology by controlling fluxes of heat, gas, and momentum between the ocean and atmosphere. Climate simulations have large systematic errors because the mixing of waters due to WTS flow is not properly modeled. Yet, these flows remain little investigated and poorly understood. We urgently need to learn how WTS mixing depends on flow parameters, but none of today's research approaches can produce the empirical data which is needed.

Project Overview

WaTurSheD presents the only practical way out of this stalemate: an extensive experimental campaign where each WTS parameter is individually controlled and systematically varied.

Experimental Facilities

I will make use of the new, large water channel laboratory at NTNU, the only facility where such an experimental campaign is currently possible. This will allow me to combine experiments with new theory and a novel data analysis method.

Goals

Through WaTurSheD, the WTS-driven mixing in the upper ocean can, for the first time, be modeled based on direct empirical evidence.

Unique Opportunity

WaTurSheD is a unique opportunity for progress, combining my group's specialized expertise on wave-current interactions through both theory and experiment, and a one-of-a-kind laboratory where my team can create a faithful, fully tunable scale model of upper ocean WTS flow.

Theoretical Advancements

The theoretical framework for ocean waves and currents must be advanced in order to accommodate the new insights, a task I will attend to myself.

Data Analysis Innovation

We will develop a completely new way to analyze near-surface turbulence. By detecting the imprints they leave on the surface using a computer vision technique, the most essential turbulent structures can be selected. This will allow trends in WTS data to emerge, which would otherwise be obscured by fast fluctuations.

Conclusion

All WaTurSheD's components will unite towards its final goal: a universal scaling law for WTS flows valid from centimeters to hundreds of meters.