Researchers Return from Central Pacific with El Niño Data

Research vessel Falkor sailed from Majuro, Marshall Islands, to Honolulu over a three-week period across the central Pacific equator. Photo credit: SOI/Carlie Wiener.

By Maui  Now Staff

An international team of scientists led by researchers from the University of Hawai‘i at Mānoa arrived in Honolulu today after studying small-scale ocean mixing under El Niño conditions while aboard the Falkor, Schmidt Ocean Institute’s research vessel.

Dr. Kelvin Richards, oceanographer at the UH Mānoa, and his team returned from a three-week research cruise in the central equatorial Pacific during strong El Niño conditions.

The expedition left Majuro, Marshall Islands, in late July and completed an 11-day time-series at the equator, giving these researchers their first view of the water profile in this region.

The science team, led by Richards, has completed similar water profiling in the western equatorial Pacific. However, this is Richards’ first time moving to the Central Pacific, and if the team sees mixing trends similar to the data collected from previous Western Pacific cruises, they will continue to move further eastward with further work.

Recent research suggests that small-scale turbulence in the ocean plays a critical—and to a certain extent—overlooked role in large ocean processes like El Niño. Accurately modeling how the ocean absorbs and moves heat is among the greatest challenges for climate change modeling, and forecasting of El Niño Southern Oscillations.

The ocean helps to regulate the Earth’s temperature with the movement of heat through vertical mixing in the ocean layers. However, ENSO alters regular ocean temperatures with anomalously warm or cold water bands that develop off the western coast of South America, causing climatic changes across the tropics and subtropics. The movement of ocean heat is especially important in understanding ENSOs, which spawn weather shifts such as flooding in relatively dry regions of the western US, droughts in typically wetter regions in the Western Pacific, and the lessening of trades and warmer temperatures in Hawai‘i.

From the water profiles collected, the data indicates that there are indeed mixing patterns.

“We are seeing small vertical-scale features in the shear present here and perhaps even stronger than in the west, giving an indication that these features are important in turbulent mixing,” said Dr. Richards.

The features that Dr. Richards alludes to are produced by a combination of factors, including wind blowing across the surface of the ocean.

“We are seeing that the equatorial region is a special place for the production of these small vertical-scale velocity structures and mixing,” said Dr. Richards.

This expedition comes after six successful collaborative research cruises with the Schmidt Ocean Institute and University of Hawai‘i. Several projects completed in 2014 have already had meaningful impact including two extensive mapping cruises in the Papahānaumokuākea Marine National Monument, which led to the discovery of several new fish species.

“Schmidt Ocean Institute is delighted to support this important research with significant implications for our
understanding of how small scale mixing processes in the ocean are interconnected with the global climate change.” said Victor Zykov, director of research for Schmidt Ocean Institute.

Research vessel Falkor will be in Honolulu through the summer and departs in early fall for another significant mapping cruise, sailing to Tamu Massif, the world’s largest underwater volcano located about 1,000 miles east of Japan. Tamu Massif is a unique undersea geographic formation, and the science team plans to explore the key interactions it has with the mid-ocean ridges using multibeam mapping systems and a marine magnetometer.

For more information about this and future expeditions, go online.

The School of Ocean and Earth Science and Technology at the University of Hawai‘i at Mānoa
was established by the Board of Regents of the University of Hawai‘i in 1988 in recognition of
the need to realign and further strengthen the excellent education and research resources
available within the University.

For more information about SOEST, go online.

The science team and some of the Falkor crew. Photo credit: SOI/Carlie Wiener.

Falkor crew and scientists deploy the conductivity, temperature and depth instrument to collect water samples at the equator. Photo credit: SOI/Carlie Wiener.

Student participant Julianna Diehl collects water samples from the central equatorial Pacific. Photo credit: SOI/Carlie Wiener.

Research vessel Falkor sailed from Majuro, Marshall Islands, to Honolulu over a three-week period across the central Pacific equator. Photo credit: SOI/Carlie Wiener.

Research vessel Falkor sailed from Majuro, Marshall Islands, to Honolulu over a three-week period across the central Pacific equator. Photo credit: SOI/Carlie Wiener.

The science team watches the CTD live from the control room on board Falkor. Photo credit: SOI/Carlie Wiener.