An Exploration of the Effects of Clouds on the Characterization of a remote Earth

Abstract

The Habitable Worlds Observatory (HWO) is an upcoming mission concept based on the recommendation of the 2020 Astronomy and Astrophysics decadal survey. A primary goal of HWO is to identify and characterize Earth-like exoplanets through reflected light spectroscopy. However, a planet’s spectrum is dynamic and only represents a time-dependent snapshot of its properties. Changing atmospheric conditions due to climate and weather patterns, particularly variation in cloud cover can significantly affect the spectrum in ways that complicate the understanding of a planet's baseline atmospheric properties. Variable cloud patchiness and cloud properties affect the detectability of atmospheric constituents, and also greatly influence the radiative transfer that determines a planet's spectrum. This has considerable implications for observations of potentially habitable exoplanets and thus it is critical to study and characterize the effects of clouds on their spectra. In this work, we construct an accurate model of a remote Earth using NASA's MERRA-2 dataset which assimilates data from a variety of satellites orbiting Earth. Utilizing the Planetary Spectrum Generator (PSG), we simulate observations of this remote Earth at different configurations using the HWO mission concepts.