Shaken and Stirred: Teaching the Next Generation of Oceanographers about Ocean Turbulence and Mixing

In the ocean there are many different processes that are associated with increased mixing. Different kinds of waves and vortices, energy input from the wind, flow over topography and more can all contribute. The concept of mixing is important to our understanding of how the ocean works. Small-scale turbulence and mixing is the last step in what is known as the “energy cascade,” the flow of energy through the ocean system, from mainly wind-driven large-scale currents and eddies that spin off into smaller and smaller eddies until eventually they reach the smallest microscopic scales where viscosity (friction) converts their kinetic energy into heat and the energy is ultimately dissipated. 

But a better understanding of mixing is important for more than just understanding ocean flows and being able to model them correctly — something that is essential for climate predictions. Mixing plays a role in many crucial ocean processes such as the uptake of carbon dioxide and heat, nutrient cycles and global overturning circulation. This is why ocean mixing has recently become a so-called “essential ocean variable,” something we measure in the ocean that is of extra importance for climate models, forecasting and more.

Members of the Multiscale Ocean Dynamics (MOD) lab at Scripps Institution of Oceanography have studied ocean mixing for decades and have pioneered novel instrumentation for measuring these very small-scale turbulent motions in the ocean. While students in the MOD lab are immersed in these techniques, many students in related fields have expressed interest in learning more about these processes. To address that need, a group of MOD-affiliated students spent the last year designing a unique student-to-student educational opportunity.

After months of preparations, writing lectures, planning experiments, sourcing instruments and packing supplies, we kicked off the 2025 edition of the course, titled COMCEPTS — Combined Ocean Mixing Course, Experiments and Practices for Turbulence Sampling.

For the first three weeks in September, 15 students from all over the West Coast, including Scripps Institution of Oceanography, UC San Diego, UCLA, UC Berkeley, University of Washington and the Center for Scientific Research and Higher Education of Ensenada, Mexico, gathered at Scripps to learn about ocean mixing and turbulence. The students attended lectures on everything from the history of turbulence measurements in the ocean and the theory behind how we sample turbulence, to recent technological developments and new sensors.

After a first week of lectures and lab visits, it was time to apply the newly acquired knowledge in real life. Thanks to generous support from the UC Ship Funds Program, the entire second week of COMCEPTS was spent aboard Scripps research vessel Robert Gordon Sproul. The participating students were trained in using the MOD lab profiling winch, a re-purposed commercial grade fishing reel we use to tow our instruments up and down behind the ship as we drive around. 

For COMCEPTS, we brought two different profiling instruments: one with optical sensors to measure the presence of chlorophyll and dissolved organic matter in the water, and one equipped with sensors to sample turbulence. We used these instruments to collect data on how the water flowing from the Point Loma Ocean Outfall pipe, a part of the Point Loma Wastewater Treatment Plant that deposits partially treated wastewater about five miles offshore, evolves over 24 hours as it interacts with ocean tides, something that involves a lot of mixing and turbulence. 

In addition, we used the shipboard CTD rosette to take water samples with one of our students looking for traces of certain bacteria in the wastewater plume, but also some more rare and specific molecules tied to human activities like caffeine, antibiotics and other drugs. The collected data will be used in the PhD research of multiple students. The third and last week of COMCEPTS was spent back on land analyzing the data we collected and writing up a cruise report. 

For some COMCEPTS students, this was not only their first time taking a class on turbulence, but also the first time being at sea or working with data they collected first-hand, an opportunity that is not afforded to everyone. As for the Scripps students organizing this course, we have also gotten some incredible hands-on experience of creating a curriculum from scratch, planning experiments and a multiday cruise, and building our teaching and teamwork skills. But most of all, COMCEPTS 2025 was a good reminder that science is best shared, and, like turbulence, sometimes that involves a bit of shaking and stirring.

The COMCEPTS organizing team consisted of Andrea Rodriguez-Marin Freudman, Ankitha Kannad, Helen Zhang, Caique Dias Luko, Charlotte Bellerjeau and myself. We wish to thank the UC Ship Funds Program for its support, members of the MOD lab for their guidance in designing and planning this course and cruise, as well as the crew and captain aboard R/V Robert Gordon Sproul for getting us safely out to sea and back to do our science.

Kerstin Bergentz is a sixth-year PhD candidate with the Multiscale Ocean Dynamics lab and Lagrangian Drifter Lab at Scripps. She researches air-sea interactions, upper ocean energy dynamics and various types of waves.