Presentation #102.279 in the session Poster Session.
The Great Oxidation Event was a period during which Earth’s atmospheric oxygen (O2) concentrations increased from ~10-5 times its present atmospheric level (PAL) to near modern levels. Using WACCM6, a three-dimensional fully-coupled Earth System Model, we simulate the atmosphere of Earth with O2 mixing ratios between 0.1% and 150% PAL. From these simulations, we calculate multiple orbits of planetary reflection/emission spectra using the Planetary Spectrum Generator. We highlight how observer angle, albedo, chemistry, and clouds affect simulated observations. Seasonal variability can change the planet’s brightness by up to a factor of 3 times for the same planetary phase. We show that inter-annual climate variations, as well as short-term variations due to clouds, can change the brightness of key spectral features (e.g. O2 and H2O) by up to a factor of 3.5 times. This variability can be observed in our synthetic spectra with a telescope concept such as LUVOIR or HabEx. The overall variability depends on atmospheric O2 concentration as a result of generally increased liquid and ice cloud atmospheric content as O2 reduces.