Response of the intermediate complexity Mars Climate Simulator to different obliquity angles

Abstract

A climate model of intermediate complexity, named the Mars Climate Simulator, has been developed based on the Portable University Model of the Atmosphere (PUMA). The main goal of this new development is to simulate the climate variations on Mars resulting from the changes in orbital parameters and their impact on the layered polar terrains (also known as permanent polar ice caps). As a first step towards transient simulations over several obliquity cycles, the model is applied to simulate the dynamical and thermodynamical response of the Martian climate system to different but fixed obliquity angles. The model is forced by the annual and daily cycle of solar insolation. Experiments have been performed for obliquities of φ = 15 • (minimum), φ = 25.2 • (present), and φ = 35 • (maximum). The resulting changes in solar insolation mainly in the polar regions impact strongly on the cross-equatorial circulation which is driven by the meridional temperature gradient and steered by the Martian topography. At high obliquity, the cross-equatorial near surface flow from the winter to the summer hemisphere is strongly enhanced compared to low obliquity periods. The summer ground temperature ranges from 200 K (φ = 15 • ) to 250 K (φ = 35 • ) at 80 • N in northern summer, and from 220 K (φ = 15 • ) to 270 K (φ = 35 • ) at 80 • S in southern summer. In the atmosphere at 1 km above ground, the respective range is 195-225 K in northern summer, and 210-250 K in southern summer.

Influence of ice rheology and dust content on the dynamics of the north-polar cap of Mars

“…Future work will encompass an improved coupling between the atmosphere and the ice cap by downscaling simulation results obtained with the atmosphere model PUMA-2 (Portable University Model of the Atmosphere, Fraedrich et al 2003; see also http://puma.dkrz.de/puma/) adapted to Martian conditions (Segschneider et al 2005). This will further improve the physical basis of the parameterizations for the surface temperature and the accumulation-ablation rate.…”

Coupling Planet Simulator Mars, a general circulation model of the Martian atmosphere, to the ice sheet model SICOPOLIS

“…The complete model package including sources and documentation is available at www.mi.uni-hamburg.de/plasim. The Planet Simulator Earth (Fraedrich et al 2005a), in particular its atmospheric module PUMA II, is the basis for the development of Planet Simulator Mars (Segschneider et al 2005), which is a spectral circulation model of the Martian atmosphere. It simulates the atmospheric motions by integration of the primitive equations.…”

“…The numerical solution of the model equations is carried out by a finite-difference integration technique. A large part of the properties of the models Planet Simulator Mars and SICOPOLIS is described in Segschneider et al (2005) and Greve et al (2004), Greve and Mahajan (2005) and Greve (2006). Therefore this paper discusses only the differences made since the publication of the aforementioned papers.…”

“…These changes constitute mainly of the coupling of the ice and atmosphere components and are covered extensively. Unlike the version described in Segschneider et al (2005), the current version of Planet Simulator Mars now includes a hydrological cycle. The parametrisation is mostly identical to that of the original Planet Simulator Earth (Fraedrich et al 2005b,a, Lunkeit et al 2004.…”

“…In its normal configuration the Planet Simulator Mars uses an orography that has been derived from the MOLA topography (Segschneider et al 2005, Smith et al 1999). This includes, naturally, the ice caps.…”