1. タイトル

A 2D numerical simulation of atmospheric convection with condensation 
of major component under early Mars condition.

2. 希望セッション記号

PS07 - Science and Exploration of Mars and Venus

3. 著者

   - 山下 達也    
   - 小高 正嗣    
   - 杉山 耕一朗  
   - 中島 健介    
   - 石渡 正樹    
   - 林 祥介      

4. 希望発表形態    [口頭 / ポスター / どちらでも]

   口頭

5. 予稿集原稿本文(英語) [英字半角300文字以内]
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In the early Martian atmosphere, it is suggested that the major
component has condensed in wide area, and scattering greenhouse effect
of CO_{2} ice cloud contributed to the warm climate (Forget et al.,
2013). The scattering greenhouse effect depends on the cloud
distribution, and convective motion would play a important role in
formation and distribution of the cloud.  However, the structure of
atmospheric convection with condensation of major component is poorly
understood.

In this study, we develop a two-dimensional cloud resolving model
including condensation of major component and perform numerical
simulation under the early Mars condition and investigate dependency
of Scr and number density of condensation nuclei (N*) on the flow
field and cloud distribution of the convection.

In the case for Scr = 1.0, the holizontally uniform cloud layer emrges
quasi-stationary above the condensation level.  Vertical velocity in
cloud layer is much smaller than those below the condensation level,
and it is 0.5 m/s at a maximum.  These characteristics are not depend
on N*. In the case for Scr = 1.35, cloud distribution is depend on N*.
As N* is smaller, condensation and non-condensation periods occur
alternately. In the condensation period, vertical velocity in the
cloud is 2-3m/s. In the non-condensation period, horizontally uniform
cloud layer forms, and the cloud density is less than the threshold
for condensation (10^{-6}kg/m^3).  Vertical velocity in the cloud
layer is 0.5 m/s at a maximum.

We conclude that the spatial and temporal structure of cloud
convection with condensation of major component vary greatly with the
values of Scr and N*, and there are two types of solutions, which are
a quasi-stationary solution that cloud distribution and flow field do
not change in time drastically, and a quasi-periodic solution that
condensation and non-condensation periods occur alternately.


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