Featured Research

from universities, journals, and other organizations

Computer Simulations Reveal The Workings Of The Dynamo Behind Earth's Magnetic Field

Date:
February 24, 2000
Source:
University Of California, Santa Cruz
Summary:
Deep in Earth's interior is a dynamo that creates the planet's magnetic field--a kind of generator driven not by spinning turbines but by swirling flows of liquid iron. The workings of this dynamo cannot be observed, but scientists have used computer simulations to gain powerful new insights into the operation of the "geodynamo" and the behavior of Earth's core.

WASHINGTON, D.C. -- Deep in Earth's interior is a dynamo that creates the planet's magnetic field--a kind of generator driven not by spinning turbines but by swirling flows of liquid iron. The workings of this dynamo cannot be observed, but scientists have used computer simulations to gain powerful new insights into the operation of the "geodynamo" and the behavior of Earth's core.

Related Articles


The first self-consistent, three-dimensional computer simulation of the geodynamo was achieved in 1995 by Gary Glatzmaier, now a professor of earth sciences at the University of California, Santa Cruz, and Paul Roberts, professor of mathematics at UCLA. Glatzmaier, Roberts, and their coworkers have since refined and extended their simulations, shedding new light on the planet's inner workings.

Glatzmaier presented the group's latest findings on Sunday, February 20, at the annual meeting of the American Association for the Advancement of Science in Washington, D.C.

The Glatzmaier-Roberts model of the geodynamo is essentially a complex set of equations describing the physics of Earth's core. Scientists had long speculated that the mechanism behind the geomagnetic field involved the motion of the Earth's fluid outer core, which surrounds a solid inner core. Both are composed mainly of iron. The solid inner core is about the size of the moon and as hot as the surface of the sun.

The flow of heat from the core ultimately drives the geodynamo. "Basically, the whole thing works because the Earth is cooling off," Glatzmaier said. The cooling process results in fluid motions in the outer core that produce an electric current, which, like any electric current, generates a magnetic field.

One of the initial achievements of the Glatzmaier-Roberts model of the geodynamo was the simulation of a reversal of Earth's magnetic field, when the north and south magnetic poles trade places. This phenomenon has occured many times in the history of the planet, according to paleomagnetic records preserved in rocks that show the direction and strength of Earth's magnetism at the time the rocks formed.

"We were able to get a magnetic field generated by the model that looks a lot like the Earth's and undergoes reversals," Glatzmaier said.

The model also predicted that the solid inner core should rotate slightly faster than the surface of the Earth. This prediction was later supported by other researchers using evidence from seismic waves that pass through the core.

Over the past five years, Glatzmaier and his coworkers have improved the precision and resolution of their model, taking advantage of advances in computer capacity. They have now run simulations spanning as much as 300,000 years and showing a pattern of magnetic-field reversals very similar to that seen in the paleomagnetic record.

"We can run the simulation for 200,000 years and the magnetic field will be stable for a very long time -- millions of time steps for which we solve these equations. Then within a thousand years it reverses polarity, and then it remains stable again for another long period. We were very happy to see that, because that's also what we see in the Earth's record," Glatzmaier said.

He noted that the reversals are not triggered by an external influence on the geodynamo. "It is simply due to the very nonlinear, chaotic nature of the dynamo system," he said.

The group's most recent efforts have focused on the role of the mantle in controlling the frequency of geomagnetic reversals. Temperature variations in the mantle, causing an uneven pattern of heat flow from the outer core into the mantle, may affect the fluid dynamics of the outer core. So Glatzmaier's group ran their simulation using eight different patterns of heat flow across the core-mantle boundary.

The results, published in the October 28, 1999, issue of the journal Nature, showed that the pattern of heat flow determined by the mantle does have a big influence on the behavior of the geodynamo. The most Earthlike pattern of magnetic-field reversals occurred with a relatively uniform heat-flow pattern. This suggests that scientists may have overestimated the extent of thermal variation in the mantle, or that variations in mantle composition may compensate for thermal variations.

"We're still far from satisfied that we have all the answers," Glatzmaier said. "The model is a way of exploring the unknown, and it looks very promising because the results are so much like the real magnetic field. But we have less confidence in the details, and that's where more powerful computers will help."

###

Additional information about the geodynamo, including color images derived from computer simulations, can be found on the Web at http://es.ucsc.edu/~glatz/geodynamo.html.


Story Source:

The above story is based on materials provided by University Of California, Santa Cruz. Note: Materials may be edited for content and length.


Cite This Page:

University Of California, Santa Cruz. "Computer Simulations Reveal The Workings Of The Dynamo Behind Earth's Magnetic Field." ScienceDaily. ScienceDaily, 24 February 2000. <www.sciencedaily.com/releases/2000/02/000224075833.htm>.
University Of California, Santa Cruz. (2000, February 24). Computer Simulations Reveal The Workings Of The Dynamo Behind Earth's Magnetic Field. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2000/02/000224075833.htm
University Of California, Santa Cruz. "Computer Simulations Reveal The Workings Of The Dynamo Behind Earth's Magnetic Field." ScienceDaily. www.sciencedaily.com/releases/2000/02/000224075833.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Arctic Warming Twice As Fast As Rest Of Planet

Arctic Warming Twice As Fast As Rest Of Planet

Newsy (Dec. 18, 2014) The Arctic is warming twice as fast as the rest of the planet, thanks in part to something called feedback. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins