Stormy Weather on the Horizon: NASA explores El Nino

Author:  Ng Elizabeth

Date:  February 2008

Have you noticed that the storm season seems to be growing more severe? Or perhaps you've noticed that the winter has been particularly cold and wet in California this winter? These weather patterns are attributed to the phenomenon called El Nino (Spanish for "The Christ Child" since the phenomenon occurs around Christmas time). El Nino is a weather pattern that brings wet winter weather and strong storms to the West Coast, Gulf States and the South East. Recently, a NASA research team has released a study that sheds new light on this phenomenon.

The findings indicated that increasing ocean surface temperatures in the eastern Pacific Ocean cause air pressure in the region to fluctuate. As the air-sea interaction changes, weather patterns can be altered. In some cases, this results in an increase in the number and intensity of wintertime storms.

To study the air-sea interactions, NASA researchers examined daily records of snow and rainfall events over 49 U.S. winters, along with ocean surface temperatures and results from computer model simulations.

They observed that warmer waters in the eastern Pacific are influenced by waters from the western Pacific as well as by changes in the surface wind. These higher sea surface temperatures increase rainfall in the south eastern Pacific, which in turn alters the positions of the jet streams in both the northern and southern hemispheres. That, ultimately, affects weather in the US and around the world.

"By studying the history of individual storms, we've made connections between changes in precipitation in the U.S. and [El Niño] events in the Pacific," said Siegfried Schubert, a meteorologist at NASA's Goddard Space Flight Center and author of the study. "We can say that there is an increase in the probability that a severe winter storm will affect regions of the U.S. if there is an El Niño event."

While some may attribute higher sea surface temperatures, and thus stronger storms to global warming, Schubert warns against drawing the connection without further study. He is also quick to point out that scientists can only use this data to predict general trends in storms, not to pinpoint the causes of specific occurrences. These results will help scientists better understand the annual patterns of severe winter storms.

Written by Elizabeth Ng

Reviewed by Charley Wang, Pooja Ghatalia

Published by Pooja Ghatalia.