SMuK 2023 – scientific programme
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UP: Fachverband Umweltphysik
UP 1: Clouds in Planetary Atmospheres (joint session EP/UP)
UP 1.5: Talk
Tuesday, March 21, 2023, 17:45–18:00, ZEU/0160
Retrieval of cloud properties using spectropolarimetric simulations of Earthshine — •Orsolya Pari1, Claudia Emde1, Michael Sterzik2, and Mihail Manev1 — 1Ludwig-Maximilians-Universität, München, Germany — 2European Southern Observatory, Garching bei München, Germany
In order to be able to interpret future observations of the atmospheres of Earth-like planets and detect signatures of life, it is important to understand Earth’s atmospheric and surface properties. Observations of Earthshine, which is sunlight scattered by Earth to the Moon, and then reflected back to Earth, make it possible to study Earth as an exoplanet.
We use the Monte Carlo radiative transfer model MYSTIC to simulate polarized spectra in the atmosphere of the Earth for Ocean and Lambertian surfaces. A water or an ice cloud layer is included and we vary the cloud parameters (cloud altitude, cloud optical thickness, effective droplet radius).
The focus is on the O2−A and H2O bands, where the degree of polarization can be higher or lower than the adjacent continuum. To quantify this behavior we use the equivalent width, which is the area in the passband between the absorption line and the simulated spectrum without absorption across a specific spectral region.
We find that the equivalent width is highly sensitive to cloud altitude and cloud optical thickness.The simulations are compared to the observations of Earthshine obtained by FORS2 at the VLT for different Sun-Earth-Moon phase angles.