Rapid Cold Tongues and Speedy Computerized Transit Delivery Systems
The research cruise that set sail from Honolulu in November 2024, aboard the R/V Sikuliaq, has concluded with promising findings. Led by principal investigators Caitlin Whalen and Gunnar Voet, the team of scientists, students, and engineers from various institutions embarked on a mission to study the behaviour of internal waves below the ocean surface.
The primary objective of the research cruise was to investigate how these internal waves may break, mix water, and affect climate patterns on a global scale, with a particular focus on the equatorial Pacific Ocean. This region is a key area for the El Niño-Southern Oscillation (ENSO) mode of climate variability.
Three subsurface moorings, spanning nearly 4,000 meters, were deployed during the cruise to gather data beyond its duration. Each mooring is equipped with about 100 internally recording sensors, and in collaboration with Oregon State University oceanographer Jim Moum, sensors directly resolving turbulence scales the size of a few inches were added to the moorings.
Preliminary analysis of the measurements shows indications of internal wave generation and propagation to greater depths. The data collected by these moorings will be recovered during a subsequent cruise planned for December 2025.
The research cruise was funded by the National Science Foundation and involved scientists, students, and engineers from UC San Diego, Seattle, Boulder, Liverpool, and Tel Aviv. Gunnar Voet, an associate researcher in the Marine Physical Laboratory at the University of California San Diego, was part of the team.
During the cruise, the team used unique observational systems like FastCTD, Epsifish, and WireWalkers to record ocean temperature, salinity, turbulence, and other parameters while moving across the surface fronts of TIWs. The cold tongue of the eastern equatorial Pacific Ocean, which plays a critical role in ENSO, was a significant focus of the study.
Life on board was not all work, as a ping-pong table and a makeshift pool were set up for relaxation, and several birthdays and a Thanksgiving Day dinner were celebrated. A ceremony was also held for those crossing the equator at sea for the first time during the voyage.
While the precise research focus of the Multiscale Ocean Dynamics (MOD) group at UC San Diego, led by Gunnar Voet, during their 2024 research cruise to the equatorial Pacific could not be ascertained from the available information, past studies at the equator have shown that ocean mixing and associated heat fluxes are vital for the heat budget of the cold tongue and have important implications for ENSO. Turbulent mixing in the cold tongue near the ocean surface has recently been found to be strongly modulated by tropical instability waves (TIWs).
As the data from the subsurface moorings is analysed and the results are published, we can expect a deeper understanding of the role of internal waves in climate patterns and the behaviour of the equatorial Pacific Ocean.
- The research cruise, led by scientists like Caitlin Whalen and Gunnar Voet, utilized a combination of science, technology, and oceanographic research to study the behavior of internal waves and their impact on climate patterns, particularly in the equatorial Pacific Ocean.
- The mission, funded by the National Science Foundation, involves a team from various institutions, including UC San Diego, Seattle, Boulder, Liverpool, and Tel Aviv, employing cutting-edge tools like FastCTD, Epsifish, and WireWalkers to gather detailed oceanographic data, contributing to advancements in the field of science.
