It is considered that extrasolar planets near stars rotate synchronously due to strong tidal force. In a synchronously rotating planet, one side is permanently illuminated while the other side is in perpetual darkness. Numerical simulations with general circulation model (GCM) is one of effective methods for accessing the habitability of synchronously rotating terrestrial planets. Joshi et al. (1997) performs a GCM simulation on a synchronously rotating planet, but their model does not contain hydrologic processes. In this study, a GCM experiment is performed for a moist atmosphere on a synchronously rotating planet, and atmospheric circulation and heat transport are examined.The models utilized here are GFD-Dennou-Club AGCM5 and DCPAM based on three-dimensional primitive equation. The atmosphere consists of water vapor and dry air. The amount of dry air is 1000 hPa in terms of globally averaged surface pressure. Planetary radiation is calculated by a band model which is tuned so that the cooling profile of the atmosphere roughly resembles that of terrestrial atmosphere. The incoming solar radiation is permanently given to one side surface. Heat capacity of the entire surface is assumed to be zero. Solar constant, gravity, and planet radius are set to be values similar to those of Earth. In a statistically equilibrium state obtained by our experiment, surface temperature averaged over the day side and the night side are 309K and 259K, respectively. Longitudinal heat transport in low latitudinal region is resulted from propagations of equatorial Kelvin wave and equatorial Rossby wave. In higher latitudinal region, baroclinic eddies contribute to heat transport from the day side to the night side. In our experiment, it seems that heating at the surface almost determines the atmospheric structure. Further investigations are necessary for examining the case with thick atmosphere.
AAS/Division for Planetary Sciences Meeting Abstracts #39
- Pub Date:
- October 2007