Temperature Of Pacific Ocean Influences Midwest Rains, Scholar Says

September 05, 1997

A correlation between summertime sea-surface temperatures in the Pacific Ocean and precipitation rates in the Great Plains may lead to improved seasonal predictions of drought and flood potentials, researchers at the University of Illinois report.

"The flood of 1993 and the drought of 1988 raised serious questions about the causes of summertime climatic fluctuations over the central United States," said Mingfang Ting, professor of atmospheric sciences at the U. of I. "The closer we come to answering those questions, the better our predictions will become. That should lessen the tremendous socio-economic impacts caused by severe floods and droughts."

To identify a clearer cause-and-effect relationship between ocean and atmosphere, Ting and graduate student Hui Wang analyzed climatological data gathered from 1950 to 1990. Included in the study were precipitation measurements collected throughout the Midwest and sea-surface temperatures from both the tropical and northern regions of the Pacific Ocean. In general, the warmer the ocean, the wetter the weather, the researchers found.

But it's not a simple matter of moisture evaporating from the Pacific Ocean being dropped over the Great Plains, Ting said. "Because the mountains along the West Coast effectively block most of the moisture arriving from the Pacific Ocean, the moisture source for the central United States is actually the Gulf of Mexico. So, the temperature of the Pacific Ocean is also influencing the moisture transport from the Gulf of Mexico."

Ting believes the sea-surface temperatures in the Pacific Ocean affect both the position and the intensity of the jet stream over the central United States, which in turn modifies the circulation pattern from the gulf. "Warmer sea-surface temperatures shift the jet stream farther south, leading to more storm activity, which pumps more moisture up from the gulf," Ting said. "In contrast, cooler sea-surface temperatures shift the jet stream farther north, resulting in reduced storm activity and drier conditions."

While meteorologists have long recognized a connection between abnormally warm or cold conditions in the tropical Pacific and precipitation rates over the United States, Ting said the relationship does not account for all the fluctuations that appeared in the 40-year study. A much stronger correlation exists between the sea-surface temperatures in the north Pacific and rainfall over the Great Plains.

"Currently, only tropical Pacific sea-surface temperatures are being plugged into the forecast model to make seasonal precipitation predictions," Ting said. "By also including the north Pacificsea-surface temperatures, I think we can obtain more accurate predictions."The researchers' findings appeared in the August issue of the Journal of Climate.


University of Illinois at Urbana-Champaign

Related Jet Stream Articles from Brightsurf:

Massive halo finally explains stream of gas swirling around the Milky Way
Astronomers at the University of Wisconsin-Madison and their colleagues have discovered that a halo of warm gas surrounding the Magellanic Clouds likely acts as a protective cocoon, shielding the dwarf galaxies from the Milky Way's own halo and contributing most of the Magellanic Stream's mass.

Origins of life: Chemical evolution in a tiny Gulf Stream
Chemical reactions driven by the geological conditions on the early Earth might have led to the prebiotic evolution of self-replicating molecules.

Glacial stream insect may tolerate warmer waters
An endangered aquatic insect that lives in icy streams fed by glaciers might not mind if the water grows warmer due to climate change.

First direct evidence of ocean mixing across the gulf stream
Study in the Proceedings of the National Academy of Sciences provides first direct evidence for Gulf Stream blender effect, identifying a new mechanism of mixing water across the swift-moving current.

A continental-scale prediction on the functional diversity of stream microbes
Climate mediates continental scale patterns of stream microbial functional diversity.

Stream pollution from mountaintop mining doesn't stay put in the water
Since the 1980s, a mountaintop mine in West Virginia has been leaching selenium into nearby streams at levels deemed unsafe for aquatic life.

Jet stream not getting 'wavier' despite Arctic warming
Rapid Arctic warming has not led to a 'wavier' jet stream around the mid-latitudes in recent decades, pioneering new research has shown.

Unusual glacier flow could be first-ever look at ice stream formation (video available)
Scientists have captured the birth of a high-speed ice feature for the first time on top of a Russian glacier.

Large atmospheric waves in the jet stream present risk to global food production
Researchers at Oxford University, together with and international colleagues, have discovered jet stream patterns that could affect up to a quarter of global food production.

Newly identified jet-stream pattern could imperil global food supplies, says study
Scientists have identified systematic meanders in the globe-circling northern jet stream that have caused simultaneous crop-damaging heat waves in widely separated breadbasket regions-a previously unquantified threat to global food production that, they say, could worsen with global warming.

Read More: Jet Stream News and Jet Stream Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.