[P-CG19] 惑星大気圏・電磁圏

[PCG19-11] Expanding the Thermodynamic Framework of the Single-Column Radiative-Convective Climate Model

*Jonathan Wade Keathley¹、Ramses Ramirez¹ (1.University of Central Florida)

キーワード：Planetary Atmospheres, Climate Modeling, Habitability

Over the past 40 years, radiative-convective climate simulations have significantly advanced, enabling more precise modeling of unique extraterrestrial environments. As experimental data improves, theoretical models must be updated to reflect these refinements. To broaden the capabilities of single-column radiative-convective climate models under extreme conditions, we revisited the foundational framework established by Kasting (1991), integrating the Redlich-Kwong equation of state (EOS) for Carbon Dioxide (CO₂). However, this EOS becomes unreliable at temperatures above 1000 K and 100 bars due to inaccuracies in its thermodynamic constants at higher regimes [Duan and Zhang (2006)]. To address this limitation, we incorporated an EOS derived from Duan et al. (1992) and Duan and Zhang (2006) to update the model's data tables for unsaturated CO₂. While the original thermodynamic tables in the model performed well for lower pressures and temperatures of H₂O and CO₂, substantial expansions were necessary to accommodate extreme conditions. Previously, the unsaturated data tables for CO₂ and H₂O covered temperature ranges of -90C to 30C and 0C to 600C, respectively, with pressures spanning 0.1 to 95 bars [Kasting (1991)]. Following the updates, the model now encompasses temperatures ranging from -90C to 2200C for CO₂ and H₂O, with pressures extending from 0.1 to 30,000 bars. Additionally, specific heat capacities for all gases, including CO₂, H₂O, H₂, N₂, and O₂, were updated using the NIST Chemistry WebBook. A routine was implemented to account for the non-ideal behavior of CO₂, which becomes significant within this expanded parameter space. These advancements enhance the model's accuracy and versatility, enabling effective characterization of exoplanetary atmospheres while advancing the exploration of extreme climates and habitable environments beyond Earth.