Abstract DGP2026-77

Ultraviolet (UV) radiation has been studied for several decades due to its importance for the emergence of life on Earth. The early Earth was exposed to high amounts of UV radiation due to high activity of the young Sun. However, there are very few constraints on the composition of the Hadean atmospheres. If Earth’s early atmosphere contained molecules that are major absorbers in the UV range, this would have consequences for the build-up and survival of prebiotic molecules. Laboratory simulations of prebiotic chemistry suggest the 189 nm to 310 nm range to be crucial for the emergence of prebiotic synthesis, which is expected to be balanced between the quantity of the UV radiation and the environmental conditions at the surface. As a consequence, building the connection between UV radiation and Earth’s early conditions demands an understanding of how much flux is capable of reaching the surface.

This research focuses on the conditions of the early Earth atmosphere and its opacity to UV radiation, since it plays an important role in the amount of radiation that reaches the surface. To accomplish this, we use AGNI, a radiative-convective atmosphere modelling framework, to simulate the temporal evolution of different potential early Earth initial environmental conditions, such as the atmosphere composition and mantle redox states. The SOCRATES radiative transfer suite was implemented to create new atmospheric opacity correlated-k tables that account for the absorption cross-sections of the UV region of multiple molecular species (H2O, CO2, H2S, N2, NH3 and SO2) based on available experimental data. We present results that show the relationship between important, yet poorly constrained, environmental parameters and the levels of ultraviolet at the Earth’s surface. Our findings are compared with existing literature and suggest that for different atmospheric compositions, a negligible amount of flux might reach the surface, implying the necessity of discovering different constraints that fit the expected Hadean environmental characteristics.