Very Wet Season Is Forecast as El Nino Gains Strength : Weather: Third warm water event in four years puzzles scientists. Satellite offers new insights into ocean current.

By ROBERT LEE HOTZ

Jan. 25, 1995 12 AM PT

TIMES SCIENCE WRITER

Scientists using a satellite to peer down on remote expanses of the Pacific Ocean said Tuesday that the disruptive ocean current known as El Nino is increasing in strength, promising more downpours in California, extended drought in the Caribbean and winter daffodils on New England ski slopes.

Government climate experts predict that the unusual current in the Pacific will shape weather in California and throughout the United States for the rest of the year. That means Southern California can expect wetter than normal weather through spring, the National Weather Service said in the first of a series of more detailed, long-range seasonal forecasts.

Among climatologists, the vast, periodic upwelling of tropical warm water--named for the Christ child because it usually appears around Christmastime--is a favorite whipping boy for the world’s weather woes.

Climate experts believe that when an El Nino appears every three to seven years, it rearranges the atmosphere’s normal currents to redirect storms and upset more predictable seasonal weather patterns. The result ranges from disastrous rains in Los Angeles to balmy, spring-like winter days in New York City.

Images from the National Aeronautics and Space Administration’s TOPEX/Poseidon satellite, which uses a radar altimeter to measure the height of the sea surface, reveal a protruding tongue of tropical warm water thousands of miles long pointing at the coast of South America.

The satellite images offer new insights into the evolution of an El Nino current. They provide a kind of topographic map of the world’s oceans. The highest areas of sea level are caused by El Nino’s warmer water and the troughs by relatively cooler currents, experts at NASA’s Jet Propulsion Laboratory said.

JPL scientists used the satellite to monitor the upwelling El Nino current over the last six months of 1994 and determined that the tropical Pacific is about 4 to 8 inches higher than normal as a result of the additional warm water--more than twice as high as during the 1992-93 El Nino.

“The satellite has observed high sea surface elevation which reflects an excessive amount of unusually warm water in the upper ocean,” said satellite project scientist Lee-Lueng Fu at JPL. The excess heat warms the water, which in turn heats the atmosphere and alters the atmospheric jet stream in unpredictable ways.

“This wave is currently occupying most of the tropical Pacific Ocean,” Fu said. “It looks like it will last another month or two.”

Experts at the National Center for Atmospheric Research in Boulder, Colo., suggest that the world is in the midst of a rare extended El Nino effect, with worldwide consequences that meteorologists do not understand.

The Northern Hemisphere is experiencing the third winter season in four years to be influenced by an El Nino’s abnormally warm waters--unprecedented during the past 50 years, weather service experts said.

“We have never quite seen something like this,” said James W. Hurrell, a climate researcher at the atmospheric research center.

In the past 40 years, there is evidence that nine El Ninos of varying strength have affected the climate. The strongest El Nino on record, recorded in 1982-83, was blamed for hurricanes in Tahiti, floods in the Midwestern United States, droughts in South Africa, failed harvests in India and devastating fires in Australia. Climate experts place the total damage attributed to that season’s El Nino at more than $8 billion.

Meteorologists had predicted a far milder El Nino effect for the winter of 1994-95, but the satellite data released by JPL on Tuesday suggest that the current is at least twice as powerful as the El Nino event two years ago.

“It is looking like a stronger El Nino year this year and this is one of the reasons California is getting these heavy rains,” said Curtis Brack, a forecast meteorologist at WeatherData Inc.

Climate experts at the National Oceanic and Atmospheric Administration said that based on their expectation of the El Nino’s effects, farmers in Zimbabwe might plan for a drought and a below-average corn harvest, while farmers in the southern United States should brace for another season of above-average rain.

The National Weather Service said the birth of the most recent El Nino, which started incubating in July, was accompanied by near-record warm temperatures around the world after two relatively cooler years attributed to the effects of the 1991 Mt. Pinatubo eruption.

Throughout 1994, equatorial ocean temperatures east of the International Date Line became increasingly warmer than normal.

An El Nino event is thought to begin when trade winds over the Pacific start to slacken and a large water mass, called a Kelvin wave, is able to move eastward along the Equator. But it is integrated into such a complex cycle of climate events that no one is certain just which is cause and which is effect.

The strength of the surface winds along the Equator controls the amount and temperature of the water that rises to the surface, which in turn determines the distribution of sea surface temperatures. This affects the distribution of rainfall, which affects the strength of the winds.

“It is thought that the warming and the increased water vapor that is released in the tropical Pacific affects the atmosphere in a train of waves that propagate around the atmosphere,” said Dan Cayan, a climate researcher at the Scripps Institution of Oceanography.

“A minor change can make all the difference in the world as to whether we are wet or dry,” he said.

* WEIRD WEATHER: How El Nino works and the damage it has caused. B2

* WEATHER WOES: Rain adds misery to soggy Valley; El Nino explained. B2

* WEATHER WOES: Record rainfall soaks (Ventura) county, B1; El Nino explained, B11