Quasi-periodic climate change on Mars.
Abstract
Evidence that the Martian climate undergoes quasi-periodic variations includes the polar layered terrain, differences between the residual polar caps, and the current net southward flow of H2O. The driving functions for these variations are oscillations in the elements of the Martian orbit coupled with precession of the Martian spin axis. These "astronomic variations" control the distribution of insolation, which in turn influences the partition of volatiles between atmospheric and surface reservoirs. When the obliquity is at or below its current value, the atmospheric pressure is controlled by the radiative balance of the polar caps; the most important parameter is the CO2 polar cap albedo, which may vary with intensity of insolation. The major effects anticipated at low obliquity are growth of the polar caps, substantial decrease in surface pressure, cessation of dust storms, release of CO2 from the regolith, and poleward migration of H2O ground ice. At high obliquity, the mass of the perennial polar caps decreases and permanent CO2 frost disappears, CO2 desorbs from the regolith at high latitudes, the surface pressure may increase to several times its current value, and the atmospheric dust load increases. Because the amount of exchangeable CO2 now in the condensed state is not well known, predictions to higher atmospheric pressure are less certain.
- Publication:
-
Mars
- Pub Date:
- 1992
- Bibcode:
- 1992mars.book.1180K
- Keywords:
-
- Climate Change;
- Mars Atmosphere;
- Periodic Variations;
- Polar Caps;
- Terrain Analysis;
- Atmospheric Pressure;
- Clouds;
- Dust;
- Water Flow;
- Lunar and Planetary Exploration