Scientists have long observed the influence of the El Nino on tropical cyclones in the Pacific and Atlantic Oceans but until recently had not been able to explain how the climate phenomenon’s peak activity along the equator in winter could affect hurricanes that develop many months later and thousands of miles away.
In an article published last week in the science journal Nature, scholars from the University of Hawaii’s School of Ocean and Earth Science and Technology and National Taiwan University discussed their discovery of an oceanic pathway through which abundant heat produced during El Nino’s peak season is drawn into the Northeastern Pacific basin just as intense hurricanes are forming in the region.
As the article explains, El Nino develops every few years as the equatorial Pacific Ocean builds up a large amount of heat beneath the surface, then turns into La Nina, when the heat is discharged out of the region.
The team — made up of UH’s Fei-Fei Jin and Julien Boucharel and I-I Lin from National Taiwan University —is the first to identify the accumulation of heat deep in the ocean as the link between El Nino and hurricane intensity.
"We did not connect the discharged heat of El Nino to the fueling of hurricanes until recently, when we noticed another line of active research in the tropical cyclone community that clearly demonstrated that a strong hurricane is able to get its energy not only from the warm surface water but also by causing warm, deep water — up to 100 meters deep — to upswell to the surface," said Jin, the lead author, in a statement released Thursday.
Boucharel, a post-doctoral researcher, explained that the Northeastern Pacific region does not typically have a significant amount of subsurface heat. Thus, when El Nino’s heat is discharged into the region, it creates conditions in which an abnormal amount of intense hurricanes may develop.
These hurricanes can pose a direct threat to Mexico, the southwestern United States and Hawaii.
The team’s findings foretell more dire consequences as the global climate continues to warm.
As tropical atmospheric circulation slows as a result of warmer climates, extra heat will be stored beneath the Northeastern Pacific region, increasing the chances for more frequent intense hurricanes, the scientists predict.
