Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Research links long droughts in U.S. to ocean temperature variations

10.03.2004


Large-scale, long-lasting droughts in the United States – such as the present one in the West -- tend to be linked to warmer than normal sea surface temperatures in the North Atlantic Ocean, and not just cooling in the tropical Pacific, according to a USGS study published today in the Proceedings of the National Academy of Sciences.

The study statistically associates the patterns of U.S. droughts during the last century to multi-decade variations in North Pacific and North Atlantic sea surface temperatures, said USGS lead author Gregory McCabe and his co-authors, USGS scientist Julio Betancourt and Mike Palecki of the Midwestern Regional Climate Center at the Illinois State Water Survey.

Although droughts remain largely unpredictable, McCabe suggests that "this research, as well as that of others, "increases concern that the current drought in the West could persist due to continuing above normal North Atlantic sea surface temperatures." The focal region of the drought may shift with the more variable North Pacific sea surface temperatures, he said.



The U.S. climate of the last century was marked by three prolonged continental-scale wet spells (1905-1930, the 1940s, and 1976-1995) and three dry spells (the 1930’s, 1950s-60s, and 1996-2004). Although researchers believe that such large and sustained shifts in U.S. precipitation are linked with the natural variability of sea surface temperatures, the mechanisms are not well understood and cannot yet be used to help predict the likelihood of droughts.

These sea surface temperature variations are characterized by climatic indices dubbed the Pacific Decadal Oscillation, or PDO, and the Atlantic Multidecadal Oscillation, or AMO. The Pacific Decadal Oscillation, or PDO index, reflects the geographic pattern of temperatures in the North Pacific Ocean and the AMO reflects basinwide temperatures in the North Atlantic Ocean. When the PDO is positive, temperatures of the central North Pacific are cool and the eastern tropical Pacific Ocean is warm. When PDO is negative, the central North Pacific is warm and the eastern tropical Pacific is cool. A positive AMO indicates warm temperatures across the entire North Atlantic Ocean and negative AMO indicates cool North Atlantic temperatures.

Both negative and positive PDO "events" in the North Pacific Ocean tend to last 20-30 years, with recent research increasingly associating these events with regional temperature and precipitation variability across the country. For example, most scientists think the PDO variability is linked to changes in the frequency and duration of El Niño or La Niña events over the course of decades.

The AMO association with U.S. climate is less well known, but recent studies suggest that variation in water temperatures in the North Atlantic affects summertime precipitation and could also regulate the strength of El Niño/La Niña effects on weather year-round, particularly in the Midwest.

The statistical study was aimed at delineating temporal and geographical variations in drought frequency and then correlating these variations with indices of Pacific and Atlantic Ocean climate . The researchers were able to correlate two of the three leading modes of drought frequency with PDO and AMO variations. The other pattern of variability, the researchers suggest, may represent a complex pattern of trends in drought frequency related to increasing Northern Hemisphere temperatures, or some other as-yet unidentified climate trend.

In general, McCabe and his coauthors suggest that large-scale droughts in the United States are likely to be associated with positive AMO -- the kind of warming of sea surface temperatures that occurred over the North Atlantic in the 1930s, 50s, and since 1995.

In contrast, wet conditions prevail over most of the country during North Atlantic cooling (negative AMO). The researchers found that cool waters in the central North Pacific are associated with drought in the Northern Rockies and Pacific Northwest, whereas warm waters in the central North Pacific are generally associated with drought in the Southwest and central Plains.

The researchers note that the best hope for predicting long-term droughts seems to lie with identifying precursor states in oceanic climate that could lead to drought.

The authors noted that persistent and widespread droughts can potentially compromise crop and livestock production, revenues from outdoor recreation and tourism, international and interstate water agreements, sustained urban growth, management of wildland fires, and even conservation efforts nationwide.

"What we hope to do eventually," said Betancourt, "is use the information on the relationship between sea surface temperatures and North American climate to help resource managers and policy makers guide the country in more effective and long-term water management strategies and to anticipate climatic effects on ecosystems."


The USGS serves the nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.

To receive USGS news releases go to http://www.usgs.gov/public/list_server.html.

Greg McCabe | EurekAlert!
Further information:
http://www.usgs.gov/

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>