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Posted by: ngunn Sep 22 2010, 10:30 PM

I think this will be of interest: http://www.sciencedaily.com/releases/2010/09/100922124546.htm

Posted by: schaffman Sep 23 2010, 10:47 AM

Some interesting dynamics going on here. If some of the CO₂ ice gets temporarily covered each season by a thin layer of water ice, you might expect some areas (shaded areas in north-facing troughs?) to retain CO₂ ice throughout the summer and become permanently incorporated into the North Pole Layered Deposits (NPLD). This suggests that the NPLD might contain significant amounts of CO₂ ice, but I don't think the spectroscopic evidence indicates this (?). Hmm.
Tom

Posted by: Juramike Sep 23 2010, 11:40 AM

The thin layer of ice might spectroscopically mask the CO2. (Like as a paint covering).

I wonder if something that penetrates deeper might notice a change, like a RADAR experiment that could measure dielectric constant. (At 0 C, dielectric constant of H2O = 88, CO2 = 1.6. [http://www.asiinstr.com/technical/Dielectric%20Constants.htm])

Posted by: schaffman Sep 23 2010, 12:37 PM

I bet it does. If there's a lot of CO2 squestered in the caps, what are the implications for past climate conditions? I wonder if there's enough there to increase the average surface pressure significantly if released. I suspect not...but...
Tom

Posted by: schaffman Sep 23 2010, 12:48 PM

Update: I just looked at Shane Byrne's review article in Annual Review of Earth and Planetary Science (2009). He says (p. 541) that "buried CO2 ice and CO2 clathrate hydrate have been eliminated as important components [of the NPLD] on the basis of thermal and mechanical strength arguments. He cites paper by Mellon (1996) and Nye et. a, (2000).

Posted by: Den Oct 20 2010, 12:26 AM

Subsurface temperatures quickly approach year-average temps: at ~20 meters, temperature barely changes. I think even at Mars poles year-average temperature is above CO2 sublimation point.