01-09-2007

Midwest Feeling Effects Of El Ni–a

BY TERESA SMITH, Times-Union Staff Writer

Temperatures in the Pacific Ocean may be responsible for record-setting warm temperatures in Indiana, according to Ken Sheeringa, Indiana associate state climatologist and professional meteorology assistant.

The Indiana State Climate Office (Iclimate), at Purdue University, where Sheeringa works, maintains the state archive of official daily and hourly weather observations recorded throughout the state.

“The primary reason for our warm weather, so far, is a strengthening episode of El Ni–o. It started out as a weak event in September and October.

“What happens is, the Pacific Ocean surface waters began to warm up near the tropics. This interacts with the atmosphere and spreads east to coasts of North and South America.”

On the west coast, storm activity increases. There is more precipitation. This could come in the form of snow as well as rain in northern California and Oregon.

“In any case,” Sheeringa said, “since the second week of December there have been above normal temperatures in Indiana, six or seven degrees higher than normal, which is quite significant.”

El Ni–o reduces snowfall amounts in the Midwest. Normally, the region has six or seven inches of snow by now. Instead, it has rained more than normal.

Sheeringa said scientists are still learning about El Ni–o’s impact. When predictions about this winter were made, El Ni–o was weak. It built up much faster than expected and “then decided to intensify faster than expected.”

“Actually, it strengthened pretty rapidly, which could be why we’re having more rainfall. How long will it last is a good question. The current trend will diminish toward spring.

“There is a lag system. It may diminish and may have impacts into the summer. There is up to a six-month lag before the atmosphere actually notices it.”

The climatologist said a good example of the lag, not related to El Ni–o, was when Mt. Pinatubo in the Philippines erupted in 1991. The impact of the volcanic activity was not noticeable until 1992, when the whole world was colder. There were frosts in June that year.

Activity in the winter months are better studied and understood.

“In summer fewer things are going on in the atmosphere. The jet streams are ‘lazier’ and weaker in summer. Weather patterns are slower and aren’t as dynamic as they are between winter’s hot and cold air masses.”

La Ni–a is a cooling of the water in the Pacific. There are also intermediate periods when nothing is going on.

“What causes them, the El Ni–os and La Ni–as, is a subject of research now.”

Sheeringa said the polar regions are warming faster than the rest of the globe.

“Our concept was that changes in the weather is a long, slow process. We thought it took centuries, millennia for change. What we’re seeing is change in 10 years, rather than 100 years.

“And we’re trying to figure out why.”

Daily and hourly weather observations can be found at the Iclimate Web site: www.agry.purdue.edu/climate/

According to the Web site, Iclimate was established in 1956 to document and study the climate of Indiana. Ever since, it has been catering to the needs of different users, namely individuals, businesses and government agencies.

Iclimate not only assists in providing climate observations and summaries, it also interprets and applies this data to solve climate-related problems at hand.




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