Mechanisms leading to a warmer climate on high obliquity planets

Abstract

A consistent finding of high obliquity simulations is that they are warmer than their low obliquity counterparts when the climate is cold. Ice-albedo feedback has been suggested as a possible mechanism. In this study, we find that warmer climate under high obliquity holds with varying insolations, including almost ice-free conditions. We try to understand the mechanisms through a series of feedback suppression experiments. Turning off the ice-albedo feedback, the temperature contrast between high and low obliquity remains significant, but it vanishes when the cloud radiation effects or the seasonal variation is turned off. This suggests the warmer climate on high obliquity planets does not rely completely on the existence of ice, and therefore holds at high insolation. In that regime, the surface temperature, and hence the cloud formation, lags behind the substellar point, leading to inefficient sunlight reflection and warmer climate.

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• Atmospheric Dynamics on Terrestrial Planets: The Seasonal Response to changes in Orbital, Rotational and Radiative Timescales
• Superhabitability of High-Obliquity and High-Eccentricity Planets
• Wetter Stratospheres on High Obliquity Planets
• System Architecture and Planetary Obliquity: Implications for Long-Term Habitability
• A novel approach to identify resonant MHD wave modes in solar pores and sunspot umbrae: $B-\omega$ analysis
• Scaling Relations for Terrestrial Exoplanet Atmospheres from Baroclinic Criticality
• Moderately High Obliquity Promotes Biospheric Oxygenation
• Climate of high obliquity exo-terrestrial planets with a three-dimensional cloud system resolving climate model
• Regime transition between eddy-driven and moist-driven circulation on High Obliquity Planets
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