Atmospheric circulations required for thick high-altitude clouds and featureless transit spectra
Abstract
The transmission spectra of exoplanet GJ 1214b and GJ 436b are featureless as measured by current instruments. According to the measured density of these planets, we have reason to believe these planets have atmospheres, and the spectroscopy features of the atmospheres are unexpectedly not shown in the transit spectra. An explanation is high-altitude clouds or hazes are optically thick enough to make the transit spectra flat in the current observed wavelength range. We analyze the atmospheric circulations and vertical mixing that are crucial for the possible existence of the thick high-altitude clouds. We perform a series of GCM simulations with different atmospheric compositions and planetary parameters to reveal the conditions that are required for showing featureless spectra, and study the dynamical processes. We also study the role of cloud particles with different sizes, compositions and spectral characteristics with a radiative transfer model and cloud physics models. Varying the compositions and sizes of the cloud particles results in different requirements for the atmospheric circulations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.P43E2939W
- Keywords:
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- 5210 Planetary atmospheres;
- clouds;
- and hazes;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 5215 Origin of life;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 5225 Early environment of Earth;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 6207 Comparative planetology;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS