2024MNRAS.529.3971M

Using a 3D General Circulation Model, the Unified Model, we present results from simulations of a tidally locked TRAPPIST-1e with varying carbon dioxide CO₂ and methane CH₄ gas concentrations, and their corresponding prescribed spherical haze profiles. Our results show that the presence of CO₂ leads to a warmer atmosphere globally due to its greenhouse effect, with the increase of surface temperature on the dayside surface reaching up to ∼14.1 K, and on the nightside up to ∼21.2 K. Increasing presence of CH₄ first elevates the surface temperature on the dayside, followed by a decrease due to the balance of tropospheric warming and stratospheric cooling. A thin layer of haze, formed when the partial pressures of CH₄ to CO₂ (pCH₄/pCO₂) = 0.1, leads to a dayside warming of ∼4.9 K due to a change in the water vapour H₂O distribution. The presence of a haze layer that formed beyond the ratio of 0.1 leads to dayside cooling. The haze reaches an optical threshold thickness when pCH₄/pCO₂ ∼ 0.4 beyond which the dayside mean surface temperature does not vary much. The planet is more favourable to maintaining liquid water on the surface (mean surface temperature above 273.15 K) when pCO₂ is high, pCH₄ is low, and the haze layer is thin. The effect of CO₂, CH₄, and haze on the dayside is similar to that for a rapidly rotating planet. On the contrary, their effect on the nightside depends on the wind structure and the wind speed in the simulation.