Sensitivity of net thermal flux to the abundance of trace gases in the lower atmosphere of Venus

Lee, Yeon Joo; Sagawa, Hideo; Haus, Rainer; Stefani, S.; Imamura, Takeshi; Titov, Dmitrij; Piccioni, G.

doi:10.1002/2016je005087

Cited by 17 publications

(32 citation statements)

References 69 publications

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“…Longer period coverage of the night hemisphere of Venus between 1.74 and 2.3 µm is essential in this respect. While most of the global cloud cover modeling studies based on the reference model (Kliore et al 1985) appear to explain many of the previously observed features (Barstow et al 2012;Haus et al 2017;Lee et al 2016), the nightside images suggest noticeable horizontal differences in the cloud structure. Insufficient data for many of the observed new features are a serious problem for understanding their origins, and new observations are very much needed.…”

Section: Discussionmentioning

confidence: 99%

Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images

Limaye

Watanabe

Yamazaki

et al. 2018

Earth Planets Space

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Since insertion into orbit on December 7, 2015, the Akatsuki orbiter has returned global images of Venus from its four imaging cameras at eleven discrete wavelengths from ultraviolet (283 and 365 nm) and near infrared (0.9-2.3 µm), to the thermal infrared (8-12 µm) from a near-equatorial orbit. The Venus Express and Pioneer Venus Orbiter missions have also monitored the planet for long periods but from polar or near-polar orbits. The wavelength coverage and views of the planet also differ for all three missions. In reflected light, the images reveal features seen near the cloud tops (~ 70 km altitude), whereas in the near-infrared images of the nightside, features seen are at mid-to lower cloud levels (~ 48-60 km altitude). The dayside cloud cover imaged at the ultraviolet wavelengths shows morphologies similar to what was observed from Mariner 10, Pioneer Venus, Galileo, Venus Express and MESSENGER. The daytime images at 0.9 and 2.02 µm also reveal some interesting features which bear similarity to the ultraviolet images. The nighttime images at 1.74, 2.26 and 2.32 µm and at 8-12 µm reveal features not seen before and show new details of the nightside including narrow wavy ribbons, curved string-like features, long-scale waves, long dark streaks, isolated bright spots, sharp boundaries and even mesoscale vortices. Some features previously seen such as circum-equatorial belts (CEBs) and occasional areal brightenings at ultraviolet (seen in Venus Express observations) of the cloud cover at ultraviolet wavelengths have not been observed thus far. Evidence for the hemispheric vortex organization of the global circulation can be seen at all wavelengths on the day-and nightsides. Akatsuki images reveal new and puzzling morphology of the complex nightside cloud cover. The cloud morphologies provide some clues to the processes occurring in the atmosphere and are thus, a key diagnostic tool when quantitative dynamical analysis is not feasible due to insufficient information.

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Section: Discussionmentioning

confidence: 99%

Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images

Limaye

Watanabe

Yamazaki

et al. 2018

Earth Planets Space

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“…For these emission spectra, we include line lists for the following molecules: CO 2 , H 2 O, CH 4 , CO, NH 3 , H 2 S, C 2 H 2 , C 2 H 4 , C 2 H 6 , HCN, O 2 , O 3 , NO, NO 2 , and SO 2 . We include collision-induced opacities (CIA) from N 2 -N 2 , O 2 -O 2 , CO 2 -CO 2 , and N 2 -CH 4 (Gruszka & Borysow 1997;Baranov et al 2004;Lee et al 2016;Bezard et al 1990;Wordsworth et al 2010;Borysow & Tang 1993;Lafferty et al 1996;Hartmann et al 2017), as well as hydrogen and helium CIA opacities (Richard et al 2012).…”

Section: Thermal Emission Spectramentioning

confidence: 99%

Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST

Morley

Kreidberg

Rustamkulov

et al. 2017

ApJ

309

359

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Nine transiting Earth-sized planets have recently been discovered around nearby late M dwarfs, including the TRAPPIST-1 planets and two planets discovered by the MEarth survey, GJ 1132b and LHS 1140b. These planets are the smallest known planets that may have atmospheres amenable to detection with JWST. We present model thermal emission and transmission spectra for each planet, varying composition and surface pressure of the atmosphere. We base elemental compositions on those of Earth, Titan, and Venus and calculate the molecular compositions assuming chemical equilibrium, which can strongly depend on temperature. Both thermal emission and transmission spectra are sensitive to the atmospheric composition; thermal emission spectra are sensitive to surface pressure and temperature. We predict the observability of each planet's atmosphere with JWST. GJ 1132b and TRAPPIST-1b are excellent targets for emission spectroscopy with JWST/MIRI, requiring fewer than 10 eclipse observations. Emission photometry for TRAPPIST-1c requires 5-15 eclipses; LHS 1140b and TRAPPIST-1d, TRAPPIST-1e, and TRAPPIST-1f, which could possibly have surface liquid water, may be accessible with photometry. Seven of the nine planets are strong candidates for transmission spectroscopy measurements with JWST, though the number of transits required depends strongly on the planets' actual masses. Using the measured masses, fewer than 20 transits are required for a 5σ detection of spectral features for GJ 1132b and six of the TRAPPIST-1 planets. Dedicated campaigns to measure the atmospheres of these nine planets will allow us, for the first time, to probe formation and evolution processes of terrestrial planetary atmospheres beyond our solar system.

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“…Collision-induced absorption is used for CO 2 -CO 2 , O 2 -O 2 , and N 2 -N 2 . The CO 2 -CO 2 absorption data, which are included in high-CO 2 models and cover a range of temperatures up to 700 K, are sourced from Moore ( 1971 ), Kasting et al ( 1984a ), Gruszka and Borysow ( 1997 ), Baranov et al ( 2004 ), Wordsworth et al ( 2010 ), and Lee et al ( 2016 ). N 2 -N 2 collision-induced absorption coefficients are calculated based on the empirical model from Lafferty et al ( 1996 ) as described in Schwieterman et al ( 2015b ).…”

Section: Modelsmentioning

confidence: 99%

The Habitability of Proxima Centauri b: Environmental States and Observational Discriminants

et al. 2018

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Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs. Although Proxima Cen b orbits within its star's habitable zone, multiple plausible evolutionary paths could have generated different environments that may or may not be habitable. Here, we use 1-D coupled climate-photochemical models to generate self-consistent atmospheres for several evolutionary scenarios, including high-O2, high-CO2, and more Earth-like atmospheres, with both oxic and anoxic compositions. We show that these modeled environments can be habitable or uninhabitable at Proxima Cen b's position in the habitable zone. We use radiative transfer models to generate synthetic spectra and thermal phase curves for these simulated environments, and use instrument models to explore our ability to discriminate between possible planetary states. These results are applicable not only to Proxima Cen b but to other terrestrial planets orbiting M dwarfs. Thermal phase curves may provide the first constraint on the existence of an atmosphere. We find that James Webb Space Telescope (JWST) observations longward of 10 μm could characterize atmospheric heat transport and molecular composition. Detection of ocean glint is unlikely with JWST but may be within the reach of larger-aperture telescopes. Direct imaging spectra may detect O4 absorption, which is diagnostic of massive water loss and O2 retention, rather than a photosynthetic biosphere. Similarly, strong CO2 and CO bands at wavelengths shortward of 2.5 μm would indicate a CO2-dominated atmosphere. If the planet is habitable and volatile-rich, direct imaging will be the best means of detecting habitability. Earth-like planets with microbial biospheres may be identified by the presence of CH4—which has a longer atmospheric lifetime under Proxima Centauri's incident UV—and either photosynthetically produced O2 or a hydrocarbon haze layer. Key Words: Planetary habitability and biosignatures—Planetary atmospheres—Exoplanets—Spectroscopic biosignatures—Planetary science—Proxima Centauri b. Astrobiology 18, 133–189.

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Sensitivity of net thermal flux to the abundance of trace gases in the lower atmosphere of Venus

Cited by 17 publications

References 69 publications

Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images

Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images

Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST

The Habitability of Proxima Centauri b: Environmental States and Observational Discriminants

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