Add Siberian snow to the list of things that can influence how bad the winter weather will be in the United States, according to new research.
Researchers discovered that snow piling up over a band of frozen tundra from Siberia to far-northern Europe may have as much effect on the climate of the U.S. as the much-better-known weather makers El Niño and La Niña.
To understand how cold (or warm) the winter season will be in the United States, researchers and weather forecasters should also take a closer look at the snow pack in northern Eurasia laid down the previous fall, said the researchers.
The findings have new significance for seasonal climate forecasts, which predict whether upcoming seasons will be colder or warmer, wetter or drier than normal. Years with extensive autumn snow in northwest Eurasia were associated with subsequent winter temperatures diving as much as 7 degrees Fahrenheit (3.8 Celsius) lower than normal near the center of North America.
While other scientists have postulated that snow cover on the Eurasian landmass has a strong effect on winters in North America, the new study is the first to narrow down the location of the area that causes the most direct effect on U.S. winters — an area in northwest Eurasia that includes part of Siberia — though the entire effective area extends as far west as northern Scandinavia.
"One difficulty in comparing previous studies is that they have used multiple definitions of Eurasian snow cover," said study author and climatologist Thomas Mote of the University of Georgia in Athens. "Our work looked at the role of various key areas of Eurasian snow cover on atmospheric circulation," including different climate patterns that are known to affect U.S. winters.
Such information can be crucial for everything from agriculture to daily life in areas that normally have brutal winters. The crucial time to look at the snow cover in Eurasia is during October and November in order to understand the upcoming winters in North America, Mote said.
Even more complexity enters the system of interrelated climate phenomena when looking at the possibility that sea ice in the Atlantic and Arctic Oceans might affect Eurasian snow cover and thus winters in North America.
"It's interesting, because it implies to us that the potential impact of this new idea could be as large or larger than El Niño and La Niña events," Mote said. A strong La Niña was blamed for much of the snows that blanketed large parts of the United States this year.
The study was published in the May 17 edition of theInternational Journal of Climatology.