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Pacific Decadal Oscillation: Another Climate Thermostat?

by Tam Moore
Capital Press, March 19, 2004

MEDFORD, Ore. -- Forget all that fuss about El Nino that you heard in the 1980s and 1990s. Write down Pacific Decadal Oscillation instead.

Greg Jones, a climatologist with Southern Oregon University, told a recent agricultural forum in Medford that what in 1999 was christened the Pacific Decadal Oscillation and a companion Arctic Oscillation are far more important to Western farmers than the El Nino phenomenon occurring along the equator.

Jones’ judgment is shared by Gregory McCabe, a Denver-based U.S. Geological Survey climatologist who spoke at the early February Upper Klamath Basin science conference.

McCabe said that, using an index built on ocean water temperatures in the North Pacific, his colleagues have been able to model Columbia Basin seasonal weather patterns, seemingly predicting streamflow up to two years in advance.

“There’s seven years of sample data, but we’ve built a model for 30- or 40-year” weather cycles, McCabe said.

What’s all the fuss about? It’s a theory that two University of Washington professors pursued. Steven Hare began the chase in 1996 working on weather and sea-condition events related to ocean fish populations. He published the work in 1999.

Nate Mantuh, the climatologist in the team, took over and put significant data on the Internet at

Just call it PDO for short, like all the weather guys do as they discover the close fit of water temperatures between Japan and the United States and movement of the high-altitude jetstream that drives prevailing seasonal storm paths.

Jones said what goes on in the North Pacific is clearly more related to West Coast weather than the upwelling of hot water along the equator. Curiously, he said, other climatologists find relationships of sorts between PDO and weather patterns on the Atlantic Seaboard.

But McCabe pointed out that while his associates made a nice model predicting Columbia River streamflows that checked out with actual data, they can’t do the same for the Klamath River, located hundreds of miles to the south.

“I think there’s an El Nino influence on Klamath weather,” McCabe said. “El Nino effects often accentuate the streamflow patterns” here.

The USGS team is looking at PDO relationships to snowpack in the West.

McCabe said he finds some long-term relationship between soil moisture drought indexes in the interior West and PDO index, and that Klamath Basin drought index readings “fairly closely” follow shifts in PDO.

Jones said he has joined the climatologist school that believes a cycle of cooler, moister weather is at hand.

“Give me another 50 years and I’ll let you know for sure,” he told the Medford orchardists and vineyard operators.

Tam Moore, Oregon Staff Writer
Pacific Decadal Oscillation: Another Climate Thermostat?
Capital Press, March 19, 2004

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