JpGU-AGU Joint Meeting 2020

Presentation information

[E] Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS07] Aqua planetology

convener:Yasuhito Sekine(Earth-Life Science Insitute, Tokyo Institute of Technology), Hidenori Genda(Earth-Life Science Institute, Tokyo Institute of Technology), Keisuke Fukushi(Institute of Nature & Environmental Technology, Kanazawa University), Tomohiro Usui(Japan Aerospace Exploration Agency)

[MIS07-P19] Numerical experiments of climate of early Mars by the use of DCPAM

*Masaki Ishiwatari1, Yoshiyuki O. Takahashi2, George L. Hashimoto3, Kiyoshi Kuramoto1, Yoshi-Yuki Hayashi2 (1.Department of Cosmosciences, Graduate school of Science, Hokkaido University, 2.Department of Planetology, Graduate School of Science, Kobe University, 3.Department of Earth Sciences, Faculty of Science, Okayama University)

Keywords:early Mars, radiative transfer, general circulation model, radiative convective equilibrium

We have been performing one- and three-dimensional numerical experiments of early Mars. In order to do those, we have developed a radiation model for a thick CO2 atmosphere, and implemented that into our general circulation model, DCPAM. The radiation model includes advances on radiative transfer calculations which were reported by our groups. The DCPAM is an atmospheric GCM, which uses primitive equation system, and a number of parameterizations, such as radiation, turbulent diffusion, surface energy budget, and condensation processes.

Numerical experiments of one-dimensional radiative convective equilibrium of pure CO2 atmosphere without radiative effects of cloud shows surface pressure dependence of surface temperature which is similar to that reported by a previous study. That is, surface temperature is highest at a surface pressure of several bars. But, the highest surface temperature is far below the freezing point.

Three-dimensional numerical experiments are also performed by the use of the general circulation model, DCPAM, with the radiation model. In the experiments, we assumed both cases with and without radiative effects of cloud. In experiments without radiative effects of cloud, global mean surface temperatures are similar to those obtained by one dimensional radiative convective equilibrium experiments. But, surface temperature increases with increasing the surface pressure. Further, in experiments with radiative effects of cloud, surface temperature is higher than freezing point. The behavior is different from that reported by previous study.

We will check the energy budget, circulation structures, and atmospheric structures obtained by the models in order to consider the difference of results between ours and previous study's.