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We are on the verge of characterizing the atmospheres of terrestrial exoplanets in the habitable zones of M dwarf stars. Due to their large planet-to-star radius ratios and higher frequency of transits, terrestrial exoplanets orbiting M dwarf stars are favorable for transmission spectroscopy. In this work, we quantify the effect that water clouds have on the amplitude of water vapor transmission spectral features of terrestrial exoplanets orbiting M dwarf stars. To do so, we make synthetic transmission spectra from general circulation model (GCM) experiments of tidally locked planets. We improve upon previous work by considering how varying a broad range of planetary parameters affects transmission spectra. We find that clouds lead to a 10-100 times increase in the number of transits required to detect water features with the James Webb Space Telescope (JWST) with varying rotation period, incident stellar flux, surface pressure, planetary radius, and surface gravity. We also find that there is a strong increase in the dayside cloud coverage in our GCM simulations with rotation periods $gtrsim 12 mathrm{days}$ for planets with Earths radius. This increase in cloud coverage leads to even stronger muting of spectral features for slowly rotating exoplanets orbiting M dwarf stars. We predict that it will be extremely challenging to detect water transmission features in the atmospheres of terrestrial exoplanets in the habitable zone of M dwarf stars with JWST. However, species that are well-mixed above the cloud deck (e.g., CO$_2$ and CH$_4$) may still be detectable on these planets with JWST.
Aims: We aim at detecting H$_2$O in the atmosphere of the hot Jupiter HD 209458 b and perform a multi-band study in the near infrared with CARMENES. Methods: The H$_2$O absorption lines from the planets atmosphere are Doppler-shifted due to the lar
Clouds have an important role in the atmospheres of planetary bodies. It is expected that, like all the planetary bodies in our solar system, exoplanet atmospheres will also have substantial cloud coverage, and evidence is mounting for clouds in a nu
With a scheduled launch in October 2018, the James Webb Space Telescope (JWST) is expected to revolutionise the field of atmospheric characterization of exoplanets. The broad wavelength coverage and high sensitivity of its instruments will allow us t
The depth-dependent abundance of both gas-phase and solid-state water within dense, quiescent, molecular clouds is important to both the cloud chemistry and gas cooling. Where water is in the gas phase, its free to participate in the network of ion-n
We use high dynamic range, high-resolution L-band spectroscopy to measure the radial velocity variations of the hot Jupiter in the tau Bootis planetary system. The detection of an exoplanet by the shift in the stellar spectrum alone provides a measur