Up close with El Nino

Most people know El Nino as an abstract, large-scale climate process that results in changing weather patterns around the world.

University of Hawaii oceanography professor Kelvin Richards just returned from a research cruise in which he actually saw it happening.

A team of researchers, led by Richards, measured small-scale ocean water mixing in the central equatorial Pacific, where warming sea temperatures have given rise to strong El Nino conditions.

Climate forecasters this year are predicting a strong El Nino season, which could bring fall and winter rainfall to drought-stricken California and heavy winter rain to the Southern and Eastern U.S.

In Hawaii, El Nino conditions make it ideal for a busy hurricane season, which continues through November, followed by a drier-than-normal winter that will worsen drought in the islands.

Arriving in Honolulu on Monday following a three-week cruise aboard the research vessel Falkor, Richards was armed with newly mined research data that might help improve El Nino computer modeling and possibly lead to better forecasting.

Richards, director of UH’s International Pacific Research Center, said his 10-member team measured surprisingly strong flows in the ocean columns near the equator. He said the currents were generated by strong bursts of westerly wind, another El Nino phenomenon.

The winds not only create surface waves, but underwater currents that cause ocean turbulence, he said. The turbulent mixing contributes to rising sea-surface temperatures, and that eventually influences the winds and atmosphere on a global scale.

Richards’ team has previously conducted similar water-column profiling in the western equatorial Pacific region. This was their first opportunity to measure ocean mixing in the central Pacific.

Richards said the flow features were even stronger in the central Pacific, a possible indicator of how important turbulent ocean mixing is to El Nino.

“Now we compare the observations to theory and models and see how well the models capture the flow features we saw,” he said. “We hope (the data) will improve the way mixing processes are represented in the models that help to predict El Nino.”

The Falkor left Majuro, Marshall Islands, in late July, and the UH team completed an 11-day time series at the equator near the international date line.

“It was in the middle of nowhere,” the scientist said.

Richards said he got lucky in the timing of the expedition, cruising into the tropics during strong El Nino conditions. He originally proposed the cruise three or four years ago, but it got delayed for various reasons.

“Last year they predicted El Nino, but it didn’t didn’t occur, probably because there weren’t any of these strong westerly (wind) events to trigger the cycle,” he said. “But the system was still well set up, and this year everything was perfect.”

The equatorial Pacific Ocean influences the earth’s temperature in the movement of heat through vertical mixing in the ocean layers.

El Nino kicks in when warm water bands conflict with the usual cooler temperatures off the west coast of South America, touching off climatic changes across the globe, including flooding in relatively dry areas of the Western U.S., droughts in typically wetter regions and the weakening of trades and warmer temperatures in Hawaii.

The Falkor is a former German fisheries enforcement vessel that was transformed into a state-of-the-art research ship by the Palo Alto, Calif.-based Schmidt Ocean Institute in 2012.

Each year, the nonprofit, created by Eric and Wendy Schmidt, invites scientific teams from around the world to carry out research aboard the 272-foot ship, which is equipped with a high-performance supercomputer and a control room with 26 computer screens for real-time monitoring.

The latest expedition follows six other expeditions with the University of Hawaii, including two extensive 2014 mapping cruises in the Papahanaumokuakea Marine National Monument, which led to the discovery of several new fish species.

The Falkor will be in Honolulu through the summer and departs in early fall for another mapping cruise, sailing to Tamu Massif, the world’s largest underwater volcano, about 1,000 miles east of Japan.

Schmidt Ocean Institute is now taking proposals for research expeditions in 2018.