Extra-Cold Winters in Northeastern North America and Northeastern Asia?

Researchers have found a mechanism that helps explain chillier winters—and the culprit is warm water.

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To gain insight into the mechanisms that control the atmospheric dynamics, the researchers sped up Earth's rotation in the simulations.

In those cases, the plume of cold air gets bigger--consistent with it being a stationary Rossby-wave plume.  Most other atmospheric features would get smaller if the planet were to spin faster.

Although it's long been known that a heat source could produce Rossby waves, which can then form plumes, this is the first time scientists have shown how the mechanism causes cooling that extends west of the heat source.

According to the researchers, the cooling effect could account for 30 to 50 percent of the temperature difference across oceans.

It also explains why the cold region is just as big for both North America and Asia, despite the continents' differences in topography and size.

The Rossby-wave induced cooling depends on heating air over warm ocean water. Since the warm currents along western ocean boundaries in both the Pacific and Atlantic are similar, the resulting cold region to their west would be similar as well.

The next step, Schneider says, is to build simulations that more realistically reflect what happens on Earth. Future simulations would incorporate more complex features like continents and cloud feedbacks.

The research was also funded by a NOAA Climate and Global Change Postdoctoral Fellowship and a David and Lucille Packard Fellowship.

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