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 MEMS chips get metatlenses
21.02.2018 | American Institute of Physics

nachricht International team publishes roadmap to enhance radioresistance for space colonization
21.02.2018 | Biogerontology Research Foundation

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: 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...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

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

The RWI/ISL-Container Throughput Index started off well in 2018

22.02.2018 | Business and Finance

FAU researchers demonstrate that an oxygen sensor in the body reduces inflammation

22.02.2018 | Health and Medicine

Histology in 3D: new staining method enables Nano-CT imaging of tissue samples

22.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>