  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 ~4.9K 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.
