Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Height ices Mars on top

21.03.2002


Martian atmosphere churns harder in south making north wetter.


Mars: height variations lead to a wet north pole.
© NASA/JPL


The changing face of the northern polar ice cap.
© NASA/JPL



Scientists have figured out why it’s wet up north - on Mars. A new computer simulation of the martian atmosphere suggests that the planet’s geography causes differences in atmospheric circulation within the northern and southern hemispheres. These differences dump more water on the martian north pole, where it adds to the seasonal ice-cap.

Mark Richardson of the California Institute of Technology in Pasadena and John Wilson of the Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey, find that the thin martian air, which is mostly carbon dioxide, rises and falls more vigorously in the southern than in the northern hemisphere1.


This difference all but disappears when the duo remove from their simulations the height variations of the martian plains. Mars’ south pole is about six kilometres higher than its north pole. By comparison, Earth’s Tibetan plateau is on average just four kilometres above sea level.

It is this height difference that makes the atmospheric circulation dissimilar in the two hemispheres, the researchers conclude. The discrepancy creates an overall south-to-north transport of water vapour as the water ice in the polar ice-caps melts during their respective summers.

Richardson and Wilson reckon that the other potential cause of the asymmetry in atmospheric circulation - the eccentricity of Mars’ orbit around the Sun -doesn’t have a major role. The shape of the orbit determines how close Mars is to the Sun around the time of the southern summer solstice. But changing this distance in the simulations doesn’t alter the asymmetry of the circulation pattern.

Hadley cells

Atmospheric circulation on Mars happens much as it does on Earth. Gases warmed at the equator rise by convection, before passing towards the poles, where they cool, sink and flow back to the equator. This creates two great lobes of circulating gas, called Hadley cells, one in each hemisphere.

The Hadley cells carry water vapour and dust picked up from the planet’s surface. Richardson and Wilson’s simulations show that Mars’ southern Hadley cell spins more vigorously. Leaking across the equator, dust and water are then borne northwards.

The Mars Global Surveyor spacecraft showed very clearly in the late 1990s that the north and south polar ice-caps are not the same. The seasonal northern ice is rough and pitted, and looks much the same all over. The southern ice, on the other hand, is sculpted by natural erosion into strange shapes, more like a permanent ice sheet.

Some of these differences may be caused by the asymmetry in circulation - although it is not yet clear how much of either ice-cap is water ice. Most of it is frozen carbon dioxide: dry ice. The Mars Odyssey spacecraft began sending data back to Earth last month, and this information is beginning to clarify how water ice is distributed over Mars.

One clear prediction of the new results concerns the formation of polar ice features called layered deposits, which are thought to consist of alternating layers of dust and ice. They have been seen at both poles, but Richardson and Wilson calculate that their growth is likely to be more rapid in the north. We haven’t watched Mars close up for long enough yet to know if this is true.

References
  1. Richardson, M. I. Wilson, R. J. A topographically forced asymmetry in the martian circulation and climate. Nature, 416, 298 - 301, (2002).


PHILIP BALL | © Nature News Service

More articles from Physics and Astronomy:

nachricht Space radiation won't stop NASA's human exploration
18.10.2017 | NASA/Johnson Space Center

nachricht Study shows how water could have flowed on 'cold and icy' ancient Mars
18.10.2017 | Brown University

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>