Lingering El Nino Bringing High Levels of Rain, Snow : Weather: Ocean warming condition was expected to end in 1992 but may continue through 1993, scientists say.

The latest El Nino effect has lingered longer than expected and is responsible for continued high levels of rain and snow in California and other parts of the nation, researchers at the National Oceanic and Atmospheric Administration said Wednesday.

They said that they had expected the current El Nino effect to end in the middle of 1992, but they now believe that it will continue through 1993. That could mean more snow and rain for the Western United States this year, although the researchers made no specific predictions.

El Nino is a weather condition triggered by warming of the water off the coast of South America. Its effects spread to the mid-Pacific and alter rainfall and temperature patterns around the world.

El Nino conditions usually arrive every three to five years and play out within a year.

Researchers said they are mystified about why the effect has lasted longer this time.

“We reached a point where we thought we’d seen all the tricks in the El Nino bag,” said Chet Ropelewski of the Climate Analysis Center. “But it is hanging on longer than it ever has in the past.”

Researchers also noted that 1992 temperatures worldwide were lower than the two previous years and attributed the decline to the June, 1991, eruption of Mt. Pinatubo in the Philippines.

The volcano sent a massive cloud of gases and tiny particles into the upper atmosphere, blocking some sunlight that normally would strike the Earth. Global temperatures dropped to their lowest levels in decades last year, in what some believe was a temporary interruption of a global warming period triggered by the so-called greenhouse effect.

Recent findings have shown that volcano-related cooling is not caused primarily by ash but by sulfur and sulfate aerosols that are emitted into the stratosphere and reflect heat from the sun. Mt. Pinatubo’s aerosols also greatly expanded the hole in the ozone layer over the Antarctic, contributing to conditions that broadened the hole’s maximum size from less than 7 million square miles to about 9 million square miles.