ENSO and PDO may help predict onset of Siberian winter
Lake Baikal. (Photo courtesy Lyubov Izmest’eva)
A unique set of data from Russia’s Lake Baikal is helping scientists connect the timing of Siberia’s harsh winters to the El Niño/Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Stephen Katz (NOAA National Marine Sanctuaries) and colleagues have found that El Niño appears to be correlated with earlier winters at Lake Baikal, and La Niña with later winters—but only when the PDO is in its cool (negative) phase.
Katz presented his analysis at the annual meeting of the American Geophysical Union last December. The study was carried out with colleagues at the National Center for Ecological Analysis and Synthesis (NCEAS), Irkutsk State University, and Wellesley College.
Baikal is the world’s largest, oldest, and most biologically diverse lake, with most of its 2,500 plant and animal species unique to the basin. A 2008 study in Global Change Biology led by Stephanie Hampton (NCEAS) found that the lake’s surface has warmed roughly 0.2°C (0.32°F) per decade since 1945. The study drew on long-term data on water temperature and organisms collected by a family of scientists associated with an Irkutsk State University field station. In their latest work, the collaborators examined the timing of winter’s onset at Lake Baikal for the 1945–2002 period and related it to the warming and cooling patterns of ENSO (centered in the eastern tropical Pacific) and the PDO (focused in the North Pacific).
Other studies have examined ENSO and cold air outbreaks over eastern Asia, but the mixed signals led Katz and colleagues to consider the PDO as a factor that helps channel ENSO-related energy from the tropics to Siberia. “When the PDO is cool, we can explain 40 to 60 percent of the variability in lake temperature seasonality through ENSO, in a place where predicting an early or late winter really matters,” says Katz.