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 NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center

nachricht Steep rise of the Bernese Alps
24.03.2017 | Universität Bern

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>