A group of researchers in Japan claims to have overturned the common belief that El Nino-like phenomena only take place in tropical regions.

The group said Monday it has found that warm water in the North Pacific heats up the atmosphere in winter and causes large-scale air movements.

By analyzing a database of ocean surface temperatures, wind speed and other elements dating back 45 years, the team of the government-affiliated Frontier Research System for Global Change found that air above the seas off northeastern Japan was heated by warm seawater in winter. The flow of warm air then affects water in other parts of the North Pacific.