Diversity of Habitable Climatology of Land Exoplanets in a ROCKE-3D GCM Perturbed Parameter Ensemble
Abstract
The habitability of a planet is not well characterized by its mean state but by its diversity of climate regimes that distribute heat and water, if present, over its surface heterogeneously, producing environmental niches that will differ in suitability for life. A planet's climate dynamics are subject to the interaction of many planetary features including: orbital dynamics, atmospheric composition, surface composition. Exoplanet observing missions will observe but a small sampling from the full diversity possible, and given many parameters that cannot be directly observed, constraining potential targets for observability of habitable climatologies is as yet a wide open area for research. This study lays foundations for understanding the climatologies of land planets in particular. Land is required not only to provide life a stable surface but also to support a stable carbonate-silicate cycle. Modeling studies have also surmised that land planets may support a wider and longer continuous habitable zone than aqua planets, both at the moist greenhouse limit and at the outer edge. Because most exoplanet climate modeling studies thus far have biased the literature sampling of the parameter space to aqua planets, Earth continents, the Sun, M stars, and extremes of atmospheric CO2 content, we fill the gaps through a perturbed parameter ensemble (PPE) in the NASA Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics general circulation model (ROCKE-3D GCM). We sample from the following ten variables: stellar temperature and spectra from observed stars, instellation, rotation period, obliquity, surface pressure, CO2 content (in N2/CO2 atmospheres), surface albedo, surface roughness, soil texture, and initial planetary water content. Statistical analysis of the mean and distributions, spatial and temporal, of the ensemble climate states is used to uncover continuous relations between the variables and several metrics of habitability and their observability. From these we derive classifications of rocky land planet climatologies, offering a modeled uncertainty context in which observed planets might occur, and set foundations for further filling the parameter space with more diverse specifications of the planet size, and compositions of the surface and atmosphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P53A..04K
- Keywords:
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- 5205 Formation of stars and planets;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 6295 Venus;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6296 Extra-solar planets;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 5430 Interiors;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS