Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Organised wind chaos on Jupiter

10.11.2005


An international team of researchers, using new computer simulations

Scientists from the Max-Planck Institute for Solar System Research, the University of Alberta in Edmonton, Canada, and the University of California Los Angeles, have now presented a new three-dimensional computer model that successfully describes and explains all important characteristics of the banded flows on Jupiter. The simulations suggest that the wind system may reach as deep as 7000 km into the planet’s atmosphere.

Driving forces are smaller, turbulent flows that are organised into the banded form by the planet’s curvature and rotation. The computer model also explains why there are two jet classes: strong and wide jets near the equator, but narrow and weak wind belts at higher latitudes. The reason is hidden deep in planet, where immense pressures cause the atmosphere to take on a metallic state. (Nature, November 10, 2005)



Jupiter, the largest planet of our solar system, offers a fascinating view. A number of Bands of different coloured clouds seem to embrace the planet like belts. These bands mirror a system of extremely strong and stable jet winds, blowing both in easterly and westerly directions. Comparisons between the measurements of the VOYAGER mission in 1979 and the recent CASSINI spacecraft show that the system remained nearly unchanged. The winds alternate direction in accordance with the clouds: they blow eastward on the equator-facing side of the dark belts, and westward on the pole-facing side. The strongest jet is centred on the equator and blows with a speed of up to 170 meter per second in easterly direction. The jets can be separated into two classes. Stronger, broader winds are grouped around the equator while the jets are higher latitudes are generally weaker and narrower.

The team of researchers from Germany, Canada, and the USA has presented the first computer simulation that models all important characteristics of Jupiter’s wind system and explains its origin. Two groups of models for the dynamics of Jupiter’s atmosphere can be distinguished: shallow and deep models. Supporters of the shallow approach apply techniques developed in meteorology on Earth to Jupiter’s atmosphere. Because the Earth’s atmosphere is very thin compared to the planet’s radius, its spherical form can be approximate with a simplified layer, which allows the computer simulations to run considerably faster. The respective models successfully produce several banded winds but fail otherwise: The equatorial jet, the strongest on Jupiter, blows in the wrong direction, and the distinction into the two classes is missing, all jets are similar.

In the 1970s Friedrich Busse, Professor Emeritus at the University of Bayreuth, Germany, developed the first deep dynamical model . He pointed out that there is an important difference between Jupiter’s and Earth’s atmospheres: Earth’s atmosphere is bounded by the planets rocky surface. Jupiter, on the other hand, is a gaseous planet. There simply is no bottom that could restrict the winds to a thin layer.

Jupiter’s atmosphere mainly consists of hydrogen and helium. The atmospheric pressure increases with depth. At some point, the hydrogen molecules are pressed so close together that they form a metallic, electrically conductive state. Jupiter’s strong magnetic field prevents any faster movement in the electrically conductive deeper regions by a mechanism that also works in an eddy current brake. This limits the fast jet flows to the outer 10 percent of the planet’s radius.

Based on the ideas by Friedrich Busse, the new computer models the dynamics of this outer layer which still comprises 7000 km in depth. The computer program has been developed by Johannes Wicht at the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, and simulates the convection-driven fluid flow in a rotating spherical shell. The results offer a novel insight into how and why Jupiter’s wind system has developed.

On earth, weather dynamics is driven by the heat coming from the sun. On Jupiter, however, heat emerging from inside the planet plays a larger role. This powerful energy source primarily drives small-scale turbulent convective motion. But the dynamics of fluids in rotating systems – like planets – exhibit some particular characteristics: these systems prefer flows which do not change along the axis of rotation. Convective motions, like tornadoes on earth, therefore try to organise themselves into cylinder-shaped columns. The cylindrical geometry is in conflict with the spherical shape of the planet.

The spherical curvature hardly affects smaller, turbulent vortex structures. There is, however, a particular vortex size where its influence becomes as important as the convective forcing. This theoretically-derived size is known as the Rhines length, after Peter B Rhines, a professor at the University of Washington, Seattle. When a vortex diameter reaches the Rhines length, the planet’s curvature starts to organize the convective kinetic energy into the jet winds. The Rhines length therefore determines not only the width but also the number of jets that fill the planetary surface.

But why are there two different classes of jets? The computer models also provide insight into this question, and confirm the theoretical principle also proposed in the article in Nature. Jet winds around the equator reach right through the planet spanning northern as well as southern hemisphere. This is not possible at higher latitudes where the winds are in contact with the electrically conductive gas region. Here, the stronger curvature of the inner boundary helps to organize the turbulent convection. When incorporating this effect into a redefined Rhines length theory, simulation, and observation all agree: these jets are narrower than, and belong to a different class as, those around the equator.

Dr Johannes Wicht | EurekAlert!
Further information:
http://www.linmpi.mpg.de

More articles from Physics and Astronomy:

nachricht NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>