Studying the Heart of El Niño

February 4, 2016

A thousand miles south of Hawaii, the air at 45,000 feet above the equatorial Pacific was a shimmering gumbo of thick storm clouds and icy cirrus haze, all cooked up by the overheated waters below.

In a Gulfstream jet more accustomed to hunting hurricanes in the Atlantic, researchers with the National Oceanic and Atmospheric Administration were cruising this desolate stretch of tropical ocean where the northern and southern trade winds meet. It’s an area that becalmed sailors have long called the doldrums, but this year it is anything but quiet.

This is the heart of the strongest El Niño in a generation, one that is pumping moisture and energy into the atmosphere and, as a result, roiling weather worldwide.

The plane, with 11 people aboard including a journalist, made its way Friday on a long westward tack, steering clear of the worst of the disturbed air to the south. Every 10 minutes, on a countdown from Mike Holmes, one of two flight directors, technicians in the rear released an instrument package out through a narrow tube in the floor. Slowed by a small parachute, the devices, called dropsondes, fell toward the water, transmitting wind speed and direction, humidity and other atmospheric data back to the plane continuously on the way down.

The information, parsed by scientists and fed into weather models, may improve forecasting of El Niño’s effect on weather by helping researchers better understand what happens here, at the starting point.

“One of the most important questions is to resolve how well our current weather and climate models do in representing the tropical atmosphere’s response to an El Niño,” said Randall Dole, a senior scientist at NOAA’s Earth System Research Laboratory and one of the lead researchers on the project. “It’s the first link in the chain.”

An El Niño forms about every two to seven years, when the surface winds that typically blow from east to west slacken. As a result, warm water that normally pools along the Equator in the western Pacific piles up toward the east instead. Because of this shift, the expanse of water — which in this El Niño has made the central and eastern Pacific as much as 5 degrees Fahrenheit hotter than usual — acts as a heat engine, affecting the jet streams that blow at high altitudes.

That, in turn, can bring more winter rain to the lower third of the United States and dry conditions to southern Africa, among El Niño’s many possible effects.

Aided by vast processing power and better data, scientists have improved the ability of their models to predict when an El Niño will occur and how strong it will be. As early as last June, the consensus among forecasters using models developed by NOAA, as well as other American and foreign agencies and academic institutions, was that a strong El Niño would develop later in the year, and it did.

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