Presentation Open Access
Presentation No. PPS03-06, JpGU Meeting 2012, Makuhari Messe, Chiba, Japan, 24 May 2012.
Abstract. The Mars Atmosphere-Ice Coupler MAIC-2 is a simple, latitudinal model that consists of a set of parameterizations for the surface temperature, the atmospheric water transport and the surface mass balance (deposition minus sublimation) of water ice. It is driven directly by the orbital parameters obliquity, eccentricity and solar longitude (Ls) of perihelion. Surface temperature is described by the Local Insolation Temperature (LIT) scheme, which uses a daily and latitude-dependent radiation balance. The sublimation rate of water is calculated by an expression for free convection, driven by density differences between water vapour and ambient air, the deposition rate follows from the assumption that any water vapour that exceeds the local saturation pressure condenses instantly, and atmospheric transport of water vapour is approximated by instantaneous mixing with a prescribed north-south gradient. Glacial flow of ice deposits is neglected. Simulations from 10 million years (Ma) ago until 10 Ma into the future predict a variable glaciation with two distinct stages. Stage 1, the period of high average obliquity prior to 4 Ma ago, is characterized by a very mobile glaciation all over the planet. During stage 2, from 4 Ma ago until today, the north polar ice deposits grow essentially monotonically; however, interrupted by erosional events at ~3.2, 1.9 and 0.7 Ma ago (when maximum amplitudes of the main 125-ka obliquity cycle occur). There is no significant new ice deposition in the south. Stage-2-like behaviour is predicted to continue into the future.