El Nino visualization (NOAA)

The term “El Nino” has become as much a part of our weather vocabulary as the words “super cell” or “derecho.”

Today, we find it amazing to learn that when one of the strongest El Ninos of the 20th Century brought damaging storms to California with heavy snow and flooding rain during the winter of 1982-83 no one was talking about El Nino.

[Weather Service joins call for a strong El Nino event]

The 1982-83 El Nino had many effects on the U.S. and other parts of the world including floods in some places and drought in others that weren’t seen as related at the time. In the U.S. these included a cooler and wetter than average winter across South while the North was warmer and drier than average.

Elsewhere, its effects included an unusually large numbers of central Pacific hurricanes with five hitting French Polynesia and the strongest hurricane on record, up to that time to hit Hawaii, Iwa, which was that year’s 12th eastern Pacific hurricane. In contrast, only six tropical storms formed in the Atlantic Basin that year and only two became hurricanes.

[Five ways a strong El Nino could affect our weather]

While the California and central Pacific storms were widely reported, no one was talking about El Nino.

Today, when the Capital Weather Gang or papers such as California’s San Jose Mercury News write about it, they usually include a little about what El Nino is without going into much detail. These stories from CWG and the Mercury News are examples:

Models and experts lean toward strong El Nino forecast for the fall

California drought: El Niño continues to build, bringing increased chances of a wet winter

It’s safe to assume that the editors wouldn’t have used “El Nino” in the headlines of either story unless they thought that most readers recognize the word and have some idea of what it means, as well as that it affects global climate.

In 1982 only a few meteorologists and oceanographers had even heard of El Nino, which had originally referred to a warming of tropical Pacific Ocean water off the coast of Peru in December. They knew it was part of a Pacific-wide shift in ocean water temperatures and atmospheric pressures. They also knew it had some effects far beyond the tropical Pacific Ocean.

The winter of 1983-83 was my first year as Weather Editor of USA TODAY and as I recall we didn’t write anything about El Nino. Neither did anyone else until 1983 as far as I can determine.

Online archives of USA TODAY are not available for our first two years, but my search of the New York Times archives—that paper has a strong tradition of good atmospheric science reporting— turned up a likely reason for no one mentioning El Nino even in early 1983: A volcano clouded meteorologists then-new satellite views of Pacific Ocean temperatures.

On December 12, 1982, a story by the New York Times’ legendary science reporter Walter Sullivan (1918-1996) was headlined: “Climate Shift Off Peru Tied To Eruption In Mexico.”

The lead of his story said: “Sulfur compounds thrown into the sky by the eruption of a Mexican volcano last spring are possibly responsible for the reappearance of the sometimes devastating aberration of climate known as El Nino.”

His story is based on a series of discussions at the American Geophysical Union’s fall meeting in San Francisco. These discussions were about an elaborate hypothesis, by established scientists, which didn’t seem crazy to attendees, on how the volcano’s emissions had disrupted the Pacific’s atmospheric circulation.

The discussions were based in part on satellite observations of Pacific Ocean temperatures from the NOAA-7 satellite, which had begun only four months earlier.

But on April 5, 1983, the Times published a long story by Sullivan with the headline, “Massive Disturbance In Ocean Brings Far-Flung Havoc,” explaining why scientists had junked the idea of the volcano having anything to do with El Nino.

In the story Sullivan describes the many signs of an impending El Nino observed before the eruption. He noted that “little heed was paid at the time” to measurements that by 1983 scientists realized were the early stages of an El Nino.

“According to Dr. Eugene Rasmusson of the National Weather Service’s Climate Analysis Center in Maryland, however,” Sullivan wrote, “The first sign of an impending El Nino, although not recognized at the time, was recorded early last year, before the El Chichon eruption, in the form of a drop in atmospheric pressures at Tahiti and Easter Island in the central and southeastern Pacific, relative to pressures at Darwin on the north coast of Australia, opposite Indonesia.”

These atmospheric pressure connections make up the “Southern Oscillation,” which was first described in a 1924 paper by the British mathematician and meteorologist Sir Gilbert Walker.

His paper also introduced the terms North Atlantic Oscillation, and North Pacific Oscillation. Since then all three terms have become much better known as scientists have leveraged observational tools and computational methods, such as satellite observations and computer models that Walker could have only dreamed about to understand how these oscillations affect weather and climate.

Walker’s goal was to find ways to predict the strength of the Indian monsoon before it began, which in the early 20th century could mean a chance to respond early to the possible famine caused by weak monsoon rains. He failed in that attempt but left a legacy for the future.

Another part of the puzzle is “El Nino,” a term used by Peruvian fishermen for the warming every few years of the Pacific Ocean along the South American Coast. They called the warming “El Nino,” which means The Christ Child when it’s capitalized, because it and the resulting decline in their catches occurred around Christmas every few years. The coastal warming cuts off water that normally upwells from below with nutrients for the food web, including fish.

Scientists call El Nino, its rough opposite, La Nina (the little girl) and a neutral phase the El Nino-Southern Oscillation (ENSO).

The big breakthrough in scientists coming to understand how the Southern Oscillation and El Nino are part of the same phenomenon came about because the huge International Geophysical Year of 1957−1958, with its collection of global observations, just happened to occur during a pretty strong El Nino.

Michael McPhaden of NOAA’s Seattle Laboratory says if the IGY had occurred in a year with no El Niño, “it’s not clear how much longer it would have taken someone to come along and figure out what’s going on.”

The final piece of the basic El Nino puzzle was solved by Jacob Bjerknes (1897–1975), who had worked with his father, Vilhelm, and other meteorologists to develop the Norwegian model of extratropical cyclones in the 1920s.

Jacob happened to be in the United States in 1940 when Germany invaded and occupied Norway. He stayed in the U.S., at the University of California at Los Angeles, where he founded the meteorology department, and where he stayed for the rest of his career.

In 1969 he made the connection between the warm water off the South American Coast with the other elements of ENSO, including the weakening of the easterly trade winds, which allows water from the warmest part of the Pacific, near Indonesia, to “slosh” back to the east, and how these changes affect jet stream winds and the weather “downstream” around the globe.

The 1982-83 El Nino led to the installation of the approximately 70 moorings across the tropical Pacific maintained by the U.S. and Japan that send back weather data, sea-surface, and underwater temperatures and other data that track ENSO in all of its phases. If another volcano ever clouds the views of satellites, forecasters will have all they need to avoid being surprised by an El Nino as they were in 1982.