Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NASA working to take the guesswork out of long-term drought prediction

07.08.2003


Dr. Bob Oglesby, senior atmospheric scientist (NASA/MSFC/Doug Stoffer)


It´s tricky, this weather business — predicting drought, floods, rain or snow, especially months in advance. But NASA scientists at the National Space Science and Technology Center in Huntsville, Ala., are working to take the guesswork out of long-term prediction.

"We´re researching methods to predict precipitation a season or more in advance," said Dr. Bob Oglesby, a senior atmospheric scientist at the research center. The key, he said, is understanding how the atmosphere interacts with the land — sometimes in a way that completely alters the expected climate of a geographic area.

"The Gulf of Mexico, for example, is what keeps the Southeast from becoming semi-arid, or in the worst-case scenario, a big desert," he said, explaining that atmospheric flow sweeps primarily from west to east. Without the gulf, states like Alabama, Tennessee and Georgia would be forced to seek moisture from the Pacific Ocean. "But a series of mountain ranges blocks the way," he said. "If it weren´t for the nearby gulf, the lush, green landscapes of Southeast might more closely resemble the semi-arid landscapes of the great plains."



Just as mountain ranges can block moisture from an entire region, ridges of atmospheric pressure act as similar obstacles — blocking out much-needed moisture where conditions are dry, resulting in a "thermal mountain effect," first identified in 1953.

"Droughts are self-perpetuating," Oglesby said. "If an area is already experiencing drought conditions, it is more likely to continue in a drought. Similarly, if an area is experiencing extremely wet conditions, that trend is also likely to continue."

This self-perpetuating cycle is due to the interaction of moisture in the soil with the atmosphere. If the amount of rain or snowfall drops below average, the soil becomes dry. Then, as the Sun heats the Earth, less moisture is available for evaporation.

With the resulting reduction in evaporation — and its cooling effects — the surface of the Earth warms, heating the atmosphere. As the atmosphere´s temperature increases, air rises. This cycle reinforces the ridge of high pressure, enhancing its abilities to block the flow of moisture from bodies of water as well as reducing the likelihood of thunderstorm formation.

Drought conditions also may be predicted by studying other factors, including sea surface temperature variations such as those associated with ocean warming effects from El Niño, and ocean cooling effects from La Niña; north Atlantic oscillation, or air flow; and snow cover in surrounding regions.

Oglesby´s research uses computer models to simulate and predict weather conditions, using data such as soil moisture, precipitation and Earth´s surface temperature. The biggest challenge in making long-term predictions, he said, is a lack of sufficient data on soil moisture, especially moisture in lower layers of the soil.

"If someone could provide us with the state of soil moisture over a sufficiently large area, we can begin to predict its impact on precipitation over the next season or two," he said. Oglesby sees hope for better data in the future from NASA remote sensing technology that gleans information using satellite or flights over select areas.

Above-average rainfall or snow in the winter or spring can increase soil moisture to levels needed to help break the cycle of drought. But an average series of short, light rain showers — common in much of the South — are not generally enough, said Oglesby. "Even though surface soil may be wetted periodically, light rains may not drop enough moisture to reach lower soil areas. These perpetually dry areas, in turn, cause top soil to dry more quickly — once again hindering the Earth´s natural cooling process."

But there is hope even in the midst of drought conditions. "Even in a dry, Alabama summer, it rains," said Oglesby, noting that large-scale circulation and thunderstorms in the summer can also break the cycle of drought. "The trick," he said, "is replenishing the moisture in the soil before it´s too late."

From NASAs Marshall Space Flight Center in Huntsville, Oglesby has co-authored three research papers since 2001, published in the Journal of Climate and the Journal of Geophysical Research. Topics include diagnosing warm season precipitation, thresholds in atmosphere-soil moisture interactions and the predictability of winter snow cover over the Western United States.

Oglesby has a bachelors degree in physical geography from the University of California in Davis and a doctorate in atmospheric dynamics from Yale University in New Haven, Conn. He is based at the Global Hydrology and Climate Center, one of seven science research centers at the National Space Science and Technology Center, a partnership with NASAs Marshall Space Flight Center, Alabama universities, industry and federal agencies.

Contact: Steve Roy, steve.roy@msfc.nasa.gov

Steve Roy | NSSTC News
Further information:
http://www.msfc.nasa.gov/news

More articles from Earth Sciences:

nachricht Stagnation in the South Pacific Explains Natural CO2 Fluctuations
23.02.2018 | Carl von Ossietzky-Universität Oldenburg

nachricht First evidence of surprising ocean warming around Galápagos corals
22.02.2018 | University of Arizona

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>