Hawai’i Researcher Leads El Niño Study in the Central Pacific

University of Hawai’i at Manoa oceanographer Dr. Kelvin Richards led a team of researchers on a three-week research cruise in the central equatorial Pacific aboard the Schmidt Ocean Institute’s research vessel Falkor, in an effort to study small scale ocean mixing under El Niño conditions. The vessel will dock in Honolulu Monday as an end to the research mission.

The team began their journey in late July after leaving Majuro, Marshall Islands and completed an 11-day series at the equator. During the research cruise, researchers were provided with the opportunity to study water profiling in the region for the first time.

Water profiling, led by Dr. Richards, has been studied previously in the western equatorial Pacific region, but this was the first time in the Central Pacific. If results from the voyage show similar mixing trends to ones previously conducted, the team plans to continue to move east to conduct additional research.

The Ocean works to assist in the regulation of the earth’s temperature by moving heat through vertical mixing in to the oceans layers. El Niño Southern Oscillations alter the temperature with anomalously warm or cold water bands that originate off the western coast of South America. The bands cause climatic changes across the tropics and subtropics.

Movement of ocean heat is important in understanding ENSO’s, which spawn weather shifts, including things like flooding in dry regions of the western United States, droughts in wetter regions of the western Pacific, and a decrease in trades and warmer temperatures in Hawai’i.

Research suggests that small scale turbulence in the ocean plays a critical role in large ocean processes like El Niño. Among the most difficult challenges for climate change modeling and forecasting of ENSOs is accurately modeling how the ocean absorbs heat.

“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, who notes that the data indicates that mixing patterns are present.

These features are produced by a combination of factors that include 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,” explained Dr. Richards.

The most recent expedition in the Central Pacific followed six successful collaborative research cruises with the Schmidt Ocean Institute and UH. Several projects were completed in 2014, including two that included mapping in the Papahānaumokuākea Marine National Monument. During the mapping expeditions, several new species of fish were discovered.

“Schimidt 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.

The research vessel will journey to Tamu Massif, the world’s largest underwater volcano located about 1,000 miles east of Japan, to conduct mapping.

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

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

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