The Weather Notebook: The Other Weathermakers

The Other Weathermakers
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Dave Thurlow, Host

Infra-red satellite image of the
Gulf Stream
El Nino and his chilly cousin La Nina have become big-time celebrities in recent years, their every move covered by media around the world, their threatened appearances inspiring fearful rumors from Peru to Australia. But the El Nino Southern Oscillation or ENSO -- to use the official title -- is not the only show in town. A couple of other large-scale, climatic cycles have been oscillating away for centuries with barely a flicker from the popular press. Hi, I'm Dave Thurlow from the Mount Washington Observatory and this is The Weather Notebook.

Rivaling El Nino in scope and violence, and far more complex in structure, is the North Atlantic Oscillation. This see-sawing of atmospheric pressure between Iceland and the Azores has a major impact on winter weather from eastern North America to Siberia, and from Greenland to the equator. Unlike El Nino, which tends to crop up every two to seven years and dissipate after a year or so, the NAO seems to occur randomly and to hang in for years or even decades.

Halfway around the world, scientists have been keeping an eye on another long-term cycle known as the Pacific Interdecadal Oscillation. Studies of snow pack in the Cascades and salmon catches in Alaska suggest that winters in the North Pacific alternate between 20 to 30 year runs of wet/cold weather and warm/dry weather.

Is it possible that all of these large-scale modes of variability are in fact parts of one vast, infinitely complicated cycle of global oscillation? Answering this question will no doubt be one of the major climatological challenges of the coming century.

Thanks today to contributing writer David Laskin, who also contributes to The Weather Notebook's new book, Soul of the Sky. For more information, visit our website, mountwashington.org. Thanks to Subaru and the National Science Foundation.