Simulation of the water environment on the present and past Mars using a Global Climate Model

Presenter: Takeshi KURODA
The early Mars (~3.8 Ga) is thought to have been a water-rich planet like the present Earth. The present Mars is a dry planet, but nevertheless, some water environments have been found as the permanent north polar cap, underground ice, and possibly salty liquid water.
We are simulating the water environment of present and past Mars using a Global Climate Model (MGCM). For the present Mars the simulated latitudinal and seasonal distributions of water vapor/ice column densities are consistent with observations, and also the HDO/H2O isotopic fractionations has been implemented, which would be of use for the investigations of the history and movement of water in comparison with observations.
Moreover, simulations of the paleoclimate on Mars, with a dense CO2 atmosphere with the surface pressure of up to 7 bars, have also been performed using the MGCM. In addition to the radiative effects of CO2/H2O vapor and ice, the addition of a few percent of H2 has contributed to reproduce the Martian paleoclimate with liquid water flow. We also estimated the distributions of fluvial and sediment discharges from the precipitation and snow accumulations, and showed the agreements with the observed valley networks with several exceptions.