[P-PS01] Outer Solar System Exploration Today, and Tomorrow

[PPS01-03] 木星成層圏のシミュレーション研究：新しい放射コードの開発と力学への影響

*黒田 剛史¹、Alexander S. Medvedev²、Jisesh Sethunadh²、Paul Hartogh² (1.東北大学大学院理学研究科 惑星プラズマ・大気研究センター、2.マックスプランク太陽系研究所)

キーワード：木星, 成層圏, 大気放射, 大気力学, 巨大ガス惑星, JUICE

We have developed a new radiation code of radiative heating and cooling for Jupiter's upper troposphere and stratosphere (10³ to 10^-3 hPa) suitable for general circulation models (GCMs). It is based on the correlated k-distribution approach, and accounts for all the major radiative mechanisms in the Jovian atmosphere (heating due to absorption of solar radiation by CH₄, and cooling in the infrared by C₂H₆, C₂H₂, CH₄ and collision-induced transitions of H₂-H₂ and H₂-He). The code can be applied for Saturn and extrasolar gas giants. Vertical 1-D calculations using this code demonstrated that temperature of Jupiter's stratosphere is close to radiative-convective equilibrium, and that the radiative relaxation time decreases exponentially with height (from 10⁸ s near the tropopause to 10⁵ s in the upper stratosphere). The latter differs from the study of Conrath et al. (1990), which showed the very long (〜10⁸ s) relaxation time approximately constant throughout the stratosphere. Our calculations with the GCM show that the radiative relaxation time suggested by Conrath et al. (1990) is too long, and cannot sustain convergence of model solutions. With the newly derived vertical profile of relaxation time, simulations converge and produce realistic temperature and wind in Jovian stratosphere.