By Sid Perkins
Warmer-than-normal sea-surface temperatures in the central Pacific lead to stronger, more frequent tropical storms and hurricanes in the North Atlantic, a new analysis suggests. Unlike the more familiar El Ni±o, or warming in the equatorial region of the eastern and central Pacific, trends in central Pacific warming alone are more predictable and may offer forecasters a more accurate method of anticipating hurricane activity during the upcoming year, scientists say.
The sea-surface warming characteristic of El Ni±o typically stretches along the equator from the coast of South America to the international date line, with the largest temperature anomalies in the eastern Pacific. During El Ni±o episodes, the number of tropical storms and hurricanes — both called cyclones — is lower than average across the North Atlantic, says Peter J. Webster, an atmospheric scientist at Georgia Tech in Atlanta. But when the equatorial sea-surface warming is concentrated only around the international date line, hurricane activity is much higher than normal, Webster and his colleagues report in the July 3 Science.
“This is a pattern that we [scientists] hadn’t really recognized before,” comments Chris Landsea, an atmospheric scientist at NOAA’s hurricane research division in Miami. He says the finding is “an advance in the field.”