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Shape of N polar cap explained, 3D structure and history from SHARAD data
ngunn
post May 27 2010, 11:39 AM
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Article from Science Daily with link to Nature paper:
http://www.sciencedaily.com/releases/2010/...00526134150.htm
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MahFL
post May 28 2010, 03:01 PM
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It's cool to learn something new about Mars. smile.gif
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schaffman
post May 28 2010, 06:49 PM
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The article says that the spiral troughs are due to erosion caused by katabatic winds that are deflected by the Coriolis force.
The problem is that the troughs spiral outward in an anti-Coriolis direction. i.e, They curve westward not eastward as would be expected. I wish I had access to the original paper. This seems to be an error in the article. Can anyone with access to paper elaborate?
Tom
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stevesliva
post May 28 2010, 09:31 PM
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They're anti-cyclonic, that is the high pressure is over the poles. The north pole looks the opposite of a hurricane in the northern hemisphere of earth. Seems to make sense to me.
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schaffman
post May 29 2010, 12:52 PM
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A cold, dense air mass moving downslope (and southward) from the pole should create a katabatic wind that curves to the west (an easterly wind).
If these winds are responsible for eroding the troughs, then you'd expect the troughs to curve to the west as viewed by an observer at the pole looking south. Instead the troughs curve to the east.
In other words, the swirl pattern viewed from space should look like a like a counterclockwise spinning cyclone, not the clockwise pattern actually seen.
Tom
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stevesliva
post Jun 17 2010, 01:14 AM
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A little more explication on this:
http://science.nasa.gov/science-news/scien...martianspirals/

Sounds like the winds are perpendicular to the gully direction?
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schaffman
post Jun 17 2010, 02:12 PM
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QUOTE (stevesliva @ Jun 16 2010, 09:14 PM) *
A little more explication on this:
http://science.nasa.gov/science-news/scien...martianspirals/

Sounds like the winds are perpendicular to the gully direction?


Thanks. That explains more.
Tom
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