Role of H₂O and CO₂ Ices in Martian Climate Changes

Author： Yokohata T. Odaka M. Kuramoto K.

ISSN： 0019-1035

Source： Icarus, Vol.159, Iss.2, 2002-10, pp. : 439-448

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Abstract

In order to study the stability of martian climate, we constructed a two-dimensional (horizontal–vertical) energy balance model. The long-term CO₂ mass exchange process between the atmosphere and CO₂ ice caps is investigated with particular attention to the effect of planetary ice distribution on the climate stability. Our model calculation suggests that high atmospheric pressure presumed for past Mars would be unstabilized if H₂O ice widely prevailed. As a result, a cold climate state might have been achieved by the condensation of atmospheric CO₂ onto ice caps. On the other hand, the low atmospheric pressure, which is buffered by the CO₂ ice cap and likely close to the present pressure, would be unstabilized if the CO₂ ice albedo decreased. This may have led the climate into a warm state with high atmospheric pressure owing to complete evaporation of CO₂ ice cap. Through the albedo feedback mechanisms of H₂O and CO₂ ices in the atmosphere-ice cap system, Mars may have experienced warm and cold climates episodically in its history. © 2002 Elsevier Science (USA).