Journal articles on the topic 'Atmospheric'
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1
Habib, Namrah, and Raymond T. Pierrehumbert. "Modeling Noncondensing Compositional Convection for Applications to Super-Earth and Sub-Neptune Atmospheres." Astrophysical Journal 961, no. 1 (January 1, 2024): 35. http://dx.doi.org/10.3847/1538-4357/ad04e2.
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Abstract Compositional convection is atmospheric mixing driven by density variations caused by compositional gradients. Previous studies have suggested that compositional gradients of atmospheric trace species within planetary atmospheres can impact convection and the final atmospheric temperature profile. In this work, we employ 3D convection-resolving simulations using Cloud Model 1 (CM1) to gain a fundamental understanding of how compositional variation influences convection and the final atmospheric state of exoplanet atmospheres. We perform 3D initial value problem simulations of noncondensing compositional convection for Earth-air, H2, and CO2 atmospheres. Conventionally, atmospheric convection is assumed to mix the atmosphere to a final, marginally stable state defined by a unique temperature profile. However, when there is compositional variation within an atmosphere, a continuous family of stable end states is possible, differing in the final state composition profile. Our CM1 simulations are used to determine which of the family of possible compositional end states is selected. Leveraging the results from our CM1 simulations, we develop a dry convective adjustment scheme for use in general circulation models (GCMs). This scheme relies on an energy analysis to determine the final adjusted atmospheric state. Our convection scheme produces results that agree with our CM1 simulations and can easily be implemented in GCMs to improve modeling of compositional convection in exoplanet atmospheres.
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Seager, Sara. "Exoplanet atmospheres: A theoretical outlook." Proceedings of the International Astronomical Union 6, S276 (October 2010): 198–207. http://dx.doi.org/10.1017/s1743921311020187.
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AbstractWith over two dozen exoplanet atmospheres observed today, the field of exoplanet atmospheres is solidly established. The highlights of exoplanet atmosphere studies include: detection of molecular spectral features; constraints on atmospheric vertical temperature structure; detection of day-night temperature gradients; and a new numerical approach to atmosphere temperature and abundance retrieval. As hot Jupiter observations and interpretation are maturing, the next frontier is super Earth atmospheres. Theoretical models of super Earth atmospheres are moving forward with observational hopes pinned on the James Webb Space Telescope, scheduled for launch in 2014. Further in the future lies direct imaging attempts to answer the enigmatic and ancient question, “Are we alone?” via atmospheric biosignatures.
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Krissansen-Totton, Joshua. "Implications of Atmospheric Nondetections for Trappist-1 Inner Planets on Atmospheric Retention Prospects for Outer Planets." Astrophysical Journal Letters 951, no. 2 (July 1, 2023): L39. http://dx.doi.org/10.3847/2041-8213/acdc26.
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Abstract JWST secondary eclipse observations of Trappist-1b seemingly disfavor atmospheres >∼1 bar since heat redistribution is expected to yield dayside emission temperature below the ∼500 K observed. Given the similar densities of Trappist-1 planets, and the theoretical potential for atmospheric erosion around late M dwarfs, this observation might be assumed to imply substantial atmospheres are also unlikely for the outer planets. However, the processes governing atmosphere erosion and replenishment are fundamentally different for inner and outer planets. Here, an atmosphere–interior evolution model is used to show that an airless Trappist-1b (and c) only weakly constrains stellar evolution, and that the odds of outer planets e and f retaining substantial atmospheres remain largely unchanged. This is true even if the initial volatile inventories of planets in the Trappist-1 system are highly correlated. The reason for this result is that b and c sit unambiguously interior to the runaway greenhouse limit, and so have potentially experienced ∼8 Gyr of X-ray and extreme ultraviolet–driven hydrodynamic escape; complete atmospheric erosion in this environment only weakly constrains stellar evolution and escape parameterizations. In contrast, e and f reside within the habitable zone, and likely experienced a comparatively short steam atmosphere during Trappist-1's pre-main sequence, and consequently complete atmospheric erosion remains unlikely across a broad swath of parameter space (e and f retain atmospheres in ∼98% of model runs). Naturally, it is still possible that all Trappist-1 planets formed volatile-poor and are all airless today. But the airlessness of b (and c) does not require this, and as such, JWST transit spectroscopy of e and f remains the best near-term opportunity to characterize the atmospheres of habitable zone terrestrial planets.
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Ragossnig, Florian, Alexander Stökl, Ernst Dorfi, Colin P. Johnstone, Daniel Steiner, and Manuel Güdel. "Interaction of infalling solid bodies with primordial atmospheres of disk-embedded planets." Astronomy & Astrophysics 618 (October 2018): A19. http://dx.doi.org/10.1051/0004-6361/201832681.
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Context. Planets that form early enough to be embedded in the circumstellar gas disk accumulate thick atmospheres of nebular gas. Models of these atmospheres need to specify the surface luminosity (i.e. energy loss rate) of the planet. This luminosity is usually associated with a continuous inflow of solid bodies, where the gravitational energy released from these bodies is the source of energy. However, if these bodies release energy in the atmosphere instead of at the surface, this assumption might not be justified. Aims. Our aim is to explore the interactions of infalling planetesimals with primordial atmospheres at an embedded phase of evolution. We investigate effects of atmospheric interaction on the planetesimals (mass loss) and the atmosphere (heating/cooling). Methods. We used atmospheric parameters from a snapshot of time-dependent evolution simulations for embedded atmospheres and simulated purely radial, infall events of siliceous planetesimals in a 1D, explicit code. We implemented energy transfer between friction, radiation transfer by the atmosphere and the body, and thermal ablation; this gives us the possibility to examine the effects on the planetesimals and the atmosphere. Results. We find that a significant amount of gravitational energy is indeed dissipated into the atmosphere, especially for larger planetary cores, which consequently cannot contribute to the atmospheric planetary luminosity. Furthermore, we examine that planetesimal infall events for cores, MC > 2M⊕, which actually result in a local cooling of the atmosphere; this is totally in contradiction with the classical model.
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Ridden-Harper, Andrew, Stevanus K. Nugroho, Laura Flagg, Ray Jayawardhana, Jake D. Turner, Ernst de Mooij, Ryan MacDonald, et al. "High-resolution Transmission Spectroscopy of the Terrestrial Exoplanet GJ 486b." Astronomical Journal 165, no. 4 (March 21, 2023): 170. http://dx.doi.org/10.3847/1538-3881/acbd39.
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Abstract Terrestrial exoplanets orbiting M-dwarf stars are promising targets for transmission spectroscopy with existing or near-future instrumentation. The atmospheric composition of such rocky planets remains an open question, especially given the high X-ray and ultraviolet flux from their host M dwarfs that can drive atmospheric escape. The 1.3 R ⊕ exoplanet GJ 486b (T eq ∼ 700 K), orbiting an M3.5 star, is expected to have one of the strongest transmission spectroscopy signals among known terrestrial exoplanets. We observed three transits of GJ 486b using three different high-resolution spectrographs: IRD on Subaru, IGRINS on Gemini-South, and SPIRou on the Canada–France–Hawai’i Telescope. We searched for atmospheric absorption from a wide variety of molecular species via the cross-correlation method, but did not detect any robust atmospheric signals. Nevertheless, our observations are sufficiently sensitive to rule out several clear atmospheric scenarios via injection and recovery tests, and extend comparative exoplanetology into the terrestrial regime. Our results suggest that GJ 486b does not possess a clear H2/He-dominated atmosphere, nor a clear 100% water-vapor atmosphere. Other secondary atmospheres with high mean molecular weights or H2/He-dominated atmospheres with clouds remain possible. Our findings provide further evidence suggesting that terrestrial planets orbiting M-dwarf stars may experience significant atmospheric loss.
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Chance, Quadry, Sarah Ballard, and Keivan Stassun. "Signatures of Impact-driven Atmospheric Loss in Large Ensembles of Exoplanets." Astrophysical Journal 937, no. 1 (September 1, 2022): 39. http://dx.doi.org/10.3847/1538-4357/ac8a97.
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Abstract The results of large-scale exoplanet transit surveys indicate that the distribution of small planet radii is likely sculpted by atmospheric loss. Several possible physical mechanisms exist for this loss of primordial atmospheres, each of which produces a different set of observational signatures. In this study, we investigate the impact-driven mode of atmosphere loss via N-body simulations. We compare the results from giant impacts, at a demographic level, to results from another commonly invoked method of atmosphere loss, photoevaporation. Applying two different loss prescriptions to the same sets of planets, we then examine the resulting distributions of planets with retained primordial atmospheres. As a result of this comparison, we identify two new pathways toward discerning the dominant atmospheric-loss mechanism at work. Both of these pathways involve using transit multiplicity as a diagnostic, in examining the results of follow-up atmospheric and radial velocity surveys.
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Watanabe, Yasuto, and Kazumi Ozaki. "Relative Abundances of CO2, CO, and CH4 in Atmospheres of Earth-like Lifeless Planets." Astrophysical Journal 961, no. 1 (January 1, 2024): 1. http://dx.doi.org/10.3847/1538-4357/ad10a2.
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Abstract Carbon is an essential element for life on Earth, and the relative abundances of major carbon species (CO2, CO, and CH4) in the atmosphere exert fundamental controls on planetary climate and biogeochemistry. Here we employed a theoretical model of atmospheric chemistry to investigate diversity in the atmospheric abundances of CO2, CO, and CH4 on Earth-like lifeless planets orbiting Sun-like (F-, G-, and K-type) stars. We focused on the conditions for the formation of a CO-rich atmosphere, which would be favorable for the origin of life. Results demonstrated that elevated atmospheric CO2 levels trigger photochemical instability of the CO budget in the atmosphere (i.e., CO runaway) owing to enhanced CO2 photolysis relative to H2O photolysis. Higher volcanic outgassing fluxes of reduced C (CO and CH4) also tend to initiate CO runaway. Our systematic examinations revealed that anoxic atmospheres of Earth-like lifeless planets could be classified in the phase space of CH4/CO2 versus CO/CO2, where a distinct gap in atmospheric carbon chemistry is expected to be observed. Our findings indicate that the gap structure is a general feature of Earth-like lifeless planets with reducing atmospheres orbiting Sun-like (F-, G-, and K-type) stars.
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Faxon, C. B., and D. T. Allen. "Chlorine chemistry in urban atmospheres: a review." Environmental Chemistry 10, no. 3 (2013): 221. http://dx.doi.org/10.1071/en13026.
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Environmental context Atmospheric chlorine radicals can affect the chemical composition of the atmosphere through numerous reactions with trace species. In urban atmospheres, the reactions of chlorine radicals can lead to effects such as increases in ozone production, thus degrading local and regional air quality. This review summarises the current understanding of atmospheric chlorine chemistry in urban environments and identifies key unresolved issues. Abstract Gas phase chlorine radicals (Cl•), when present in the atmosphere, react by mechanisms analogous to those of the hydroxyl radical (OH•). However, the rates of the Cl•-initiated reactions are often much faster than the corresponding OH• reactions. The effects of the atmospheric reactions of Cl• within urban environments include the oxidation of volatile organic compounds and increases in ozone production rates. Although concentrations of chlorine radicals are typically low compared to other atmospheric radicals, the relatively rapid rates of the reactions associated with this species lead to observable changes in air quality. This is particularly evident in the case of chlorine radical-induced localised increases in ozone concentrations. This review covers five aspects of atmospheric chlorine chemistry: (1) gas phase reactions; (2) heterogeneous and multi-phase reactions; (3) observational evidence of chlorine species in urban atmospheres; (4) regional modelling studies and (5) areas of uncertainty in the current state of knowledge.
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Radmilović-Radjenović, Marija, Martin Sabo, and Branislav Radjenović. "Transport Characteristics of the Electrification and Lightning of the Gas Mixture Representing the Atmospheres of the Solar System Planets." Atmosphere 12, no. 4 (March 29, 2021): 438. http://dx.doi.org/10.3390/atmos12040438.
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Electrification represents a fundamental process in planetary atmospheres, widespread in the Solar System. The atmospheres of the terrestrial planets (Venus, Earth, and Mars) range from thin to thick are rich in heavier gases and gaseous compounds, such as carbon dioxide, nitrogen, oxygen, argon, sodium, sulfur dioxide, and carbon monoxide. The Jovian planets (Jupiter, Saturn, Uranus, and Neptune) have thick atmospheres mainly composed of hydrogen and helium involving. The electrical discharge processes occur in the planetary atmospheres leading to potential hazards due to arcing on landers and rovers. Lightning does not only affect the atmospheric chemical composition but also has been involved in the origin of life in the terrestrial atmosphere. This paper is dealing with the transport parameters and the breakdown voltage curves of the gas compositions representing atmospheres of the planets of the Solar System. Ionization coefficients, electron energy distribution functions, and the mean energy of the atmospheric gas mixtures have been calculated by BOLSIG+. Transport parameters of the carbon dioxide rich atmospheric compositions are similar but differ from those of the Earth’s atmosphere. Small differences between parameters of the Solar System’s outer planets can be explained by a small abundance of their constituent gases as compared to the abundance of hydrogen. Based on the fit of the reduced effective ionization coefficient, the breakdown voltage curves for atmospheric mixtures have been plotted. It was found that the breakdown voltage curves corresponding to the atmospheres of Solar System planets follow the standard scaling law. Results of calculations satisfactorily agree with the available data from the literature. The minimal and the maximal value of the voltage required to trigger electric breakdown is obtained for the Martian and Jupiter atmospheres, respectively.
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Chouqar, J., Z. Benkhaldoun, A. Jabiri, J. Lustig-Yaeger, A. Soubkiou, and A. Szentgyorgyi. "Properties of sub-Neptune atmospheres: TOI-270 system." Monthly Notices of the Royal Astronomical Society 495, no. 1 (May 2, 2020): 962–70. http://dx.doi.org/10.1093/mnras/staa1198.
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ABSTRACT We investigate the potential for the James Webb Space Telescope (JWST) to detect and characterize the atmospheres of the sub-Neptunian exoplanets in the TOI-270 system. Sub-Neptunes are considered more likely to be water worlds than gas dwarfs. We model their atmospheres using three atmospheric compositions – two examples of hydrogen-dominated atmospheres and a water-dominated atmosphere. We then simulate the infrared transmission spectra of these atmospheres for JWST instrument modes optimized for transit observation of exoplanet atmospheres: NIRISS, NIRSpec, and MIRI. We then predict the observability of each exoplanet’s atmosphere. TOI-270c and d are excellent targets for detecting atmospheres with JWST transmission spectroscopy, requiring only 1 transit observation with NIRISS, NIRSpec, and MIRI; higher signal-to-noise ratio can be obtained for a clear H-rich atmosphere. Fewer than three transits with NIRISS and NIRSpec may be enough to reveal molecular features. Water-dominated atmospheres require more transits. Water spectral features in water-dominated atmospheres may be detectable with NIRISS in two or three transits. We find that the detection of spectral features in a cloudy, H-rich atmosphere does not require integrations as long as those required for the water-dominated atmosphere, which is consistent with the differences in atmospheric mean molecular weight. TOI-270c and d could be prime targets for JWST transit observations of sub-Neptune atmospheres. These results provide useful predictions for observers who may propose to use JWST to detect and characterize the TOI-270 planet atmospheres.
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Sun, Dongdong, and Haijing Zheng. "Simulation Study of Infrared Transmittance Under Different Atmospheric Conditions." Journal of Physics: Conference Series 2356, no. 1 (October 1, 2022): 012045. http://dx.doi.org/10.1088/1742-6596/2356/1/012045.
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This article analyzes the atmospheric transmittance in the infrared band under different atmosphere conditions based on the MODTRAN software. Firstly, the atmospheric transmittance in the infrared band under two different atmospheric types, cold-dry and warm-wet, are calculated. Subsequently, the effect of H2O, CO2 and O3 molecules on the atmospheric transmittance in the infrared band are analyzed. Secondly, the differences in atmospheric transmittance at different altitudes (troposphere, stratosphere, mesosphere, thermosphere) in the infrared band are calculated, and the effects of H2O, CO2 and O3, CH4 and N2 on atmospheric transmittance and their variation patterns are analyzed. Finally, the influence of different aerosol types on atmospheric transmittance is calculated and analyzed, mainly considering molecular scattering and five different types of aerosol scattering. Conclusion, i) The total atmospheric transmittance of cold-dry atmospheres is higher than that of warm-wet atmospheres. The main factors influencing the difference in atmospheric transmittance between the two are H2O and O3. ii) Atmospheric transmittance varies with altitude, with the most dramatic changes with altitude being in the troposphere and stratosphere. The factors that have a greater influence on the atmospheric transmittance in the troposphere are H2O and CO2; CO2, O3 and CH4 have great influence on stratospheric atmospheric transmittance; The atmospheric transmittance of the mesosphere has little change, almost 1. The fluctuation of its transmittance curve is mainly affected by O3; The atmospheric transmittance of thermosphere is almost 1; N2 has little effect on atmospheric transmittance. iii) The influence of molecular scattering on atmospheric transmittance is negligible, while aerosol scattering has a great influence on atmospheric transmittance; Aerosol scattering at 9 μm has the greatest influence on atmospheric transmittance. The research results of this paper have certain guiding significance for the design and performance evaluation of infrared systems under different application conditions.
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Schaefer, Laura K., and Vivien Parmentier. "The Air Over There: Exploring Exoplanet Atmospheres." Elements 17, no. 4 (August 1, 2021): 257–63. http://dx.doi.org/10.2138/gselements.17.4.257.
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The atmospheric composition for a rocky exoplanet will depend strongly on the planet’s bulk composition and orbital position. Nontraditional gases may be present in the atmospheres of exceptionally hot planets. Atmospheres of more clement planets will depend on the abundance of volatiles acquired during planet formation and atmospheric removal processes, including escape, condensation, and reaction with the surface. To date, observations of exoplanet atmospheres have focused on giant planets, but future space-and ground-based observatories will revolutionize the precision and spectral resolution with which we can probe an exoplanet’s atmosphere. This article consolidates lessons learned from the study of giant planet atmospheres, and points to the observations and challenges on the horizon for terrestrial planets.
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Herbst, Konstantin, Saša Banjac, and Tom A. Nordheim. "Revisiting the cosmic-ray induced Venusian ionization with the Atmospheric Radiation Interaction Simulator (AtRIS)." Astronomy & Astrophysics 624 (April 2019): A124. http://dx.doi.org/10.1051/0004-6361/201935152.
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Context. Cosmic ray bombardment represents a major source of ionization in planetary atmospheres. The higher the energy of the primary cosmic ray particles, the deeper they can penetrate into the atmosphere. In addition, incident high energy cosmic ray particles induce extensive secondary particle cascades (“air showers”) that can contain up to several billion secondary particles per incoming primary particle. To quantify cosmic ray-induced effects on planetary atmospheres it is therefore important to accurately model the entire secondary particle cascade. This is particularly important in thick planetary atmospheres where the secondary particle cascades can develop extensively before being absorbed by the surface. Aims. Inside the Venusian atmosphere, cosmic rays are the dominant driver for the ionization below an altitude of ~100 km. In this work we revisit the numerical modeling of the galactic and solar cosmic-ray induced atmospheric ionization for cosmic ray ions from Hydrogen (Z = 1) to Nickel (Z = 28) and investigate the influence of strong solar energetic particle events inside the Venusian atmosphere. Methods. The Atmospheric Radiation Interaction Simulator (AtRIS), a newly developed simulation code to model the interaction of the near-(exo)planet particle and radiation field with the (exo)planetary atmosphere, was used to revisit the modeling of the altitude-dependent Venusian atmospheric ionization. Thereby, spherical geometry, the newest version of Geant4 (10.5) as well as the newest Geant4-based hadronic and electromagnetic interaction models were utilized. Results. Based on our new model approach we show that previous studies may have underestimated the galactic cosmic ray-induced atmospheric ion pair production by, amongst others, underestimating the influence of galactic cosmic ray protons above 1 TeV/nuc. Furthermore, we study the influence of 71 exceptionally strong solar particle events that were measured as Ground Level Enhancements at the Earth’s surface, and show a detailed analysis of the impact of such strong events on the Venusian ionization.
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Springsklee, Christina, Bettina Scheu, Christoph Seifert, Michael Manga, Corrado Cimarelli, Damian Gaudin, Oliver Trapp, and Donald B. Dingwell. "gas-tight shock tube apparatus for laboratory volcanic lightning under varying atmospheric conditions." Volcanica 6, no. 2 (November 23, 2023): 437–45. http://dx.doi.org/10.30909/vol.06.02.437445.
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Explosive volcanic eruptions generate electrical discharges, a phenomenon termed volcanic lightning (VL). VL is increasingly well-investigated and monitored for modern eruptions, however volcanism has been active since Earth’s origin. Thus, investigating VL under different atmospheric conditions is relevant for studies of early atmospheric chemistry and potential prebiotic reactions. We developed an experimental setup to investigate VL in varying atmospheres. We present the first experiments of laboratory discharges in particle-laden jets in varying atmospheric conditions. The new experimental setup is a mobile fragmentation bomb erupting into a gas-tight particle collector tank. This setup enables the testing of different atmospheric conditions, changes in the carrier gas of the jet, changes in the pressure within the tank, monitoring of the jet behaviour, and sampling of the atmosphere together with the decompressed solid materials. We find that the number and magnitude of near-vent electrical discharge events are similar in CO2-CO and air atmospheres.
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Miller-Ricci, Eliza, Sara Seager, and Dimitar Sasselov. "The Atmospheres of Extrasolar Super-Earths." Proceedings of the International Astronomical Union 4, S253 (May 2008): 263–71. http://dx.doi.org/10.1017/s1743921308026483.
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AbstractExtrasolar super-Earths (1-10 M⊕) are likely to exist with a wide range of atmospheres. While a number of these planets have already been discovered through radial velocities and microlensing, it will be the discovery of the firsttransitingsuper-Earths that will open the door to a variety of follow-up observations aimed at characterizing their atmospheres. Super-Earths may fill a large range of parameter space in terms of their atmospheric composition and mass. Specifically, some of these planets may have high enough surface gravities to be able to retain large hydrogen-rich atmosphseres, while others will have lost most of their hydrogen to space over the planet's lifetime, leaving behind an atmosphere more closely resembling that of Earth or Venus. The resulting composition of the super-Earth atmosphere will therefore depend strongly on factors such as atmospheric escape history, outgassing history, and the level of stellar irradiation that it receives. Here we present theoretical models of super-Earth emission and transmission spectra for a variety of possible outcomes of super-Earth atmospheric composition ranging from hydrogen-rich to hydrogen-poor. We focus on how observations can be used to differentiate between the various scenarios and constrain atmospheric composition.
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Zhang, Xi, Cheng Li, Huazhi Ge, and Tianhao Le. "The Inhomogeneity Effect. III. Weather Impacts on the Heat Flow of Hot Jupiters." Astrophysical Journal 957, no. 1 (October 23, 2023): 22. http://dx.doi.org/10.3847/1538-4357/acee7d.
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Abstract The interior flux of a giant planet impacts atmospheric motion, and the atmosphere dictates the interior’s cooling. Here we use a non-hydrostatic general circulation model (Simulating Non-hydrostatic Atmospheres on Planets) coupled with a multi-stream multi-scattering radiative module (High-performance Atmospheric Radiation Package) to simulate the weather impacts on the heat flow of hot Jupiters. We found that the vertical heat flux is primarily transported by convection in the lower atmosphere and regulated by dynamics and radiation in the overlying radiation-circulation zone. The temperature inversion occurs on the dayside and reduces the upward radiative flux. The atmospheric dynamics relay the vertical heat transport until the radiation becomes efficient in the upper atmosphere. The cooling flux increases with atmospheric drag due to increased day–night contrast and spatial inhomogeneity. The temperature dependence of the infrared opacity greatly amplifies the opacity inhomogeneity. Although atmospheric circulation could transport heat downward in a narrow region above the radiative-convective boundary, the opacity inhomogeneity effect overcomes the dynamical effect and leads to a larger overall interior cooling than the local simulations with the same interior entropy and stellar flux. The enhancement depends critically on the equilibrium temperature, drag, and atmospheric opacity. In a strong-drag atmosphere hotter than 1600 K, a significant inhomogeneity effect in three-dimensional (3D) models can boost interior cooling several-fold compared to the 1D radiative-convective equilibrium models. This study confirms the analytical argument of the inhomogeneity effect in the companion papers by Zhang. It highlights the importance of using 3D atmospheric models in understanding the inflation mechanisms of hot Jupiters and giant planet evolution in general.
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Moses, Julianne I. "Chemical kinetics on extrasolar planets." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2014 (April 28, 2014): 20130073. http://dx.doi.org/10.1098/rsta.2013.0073.
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Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures , and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. I review these disequilibrium processes in detail, discuss observational consequences and examine some of the current evidence for kinetic processes on extrasolar planets.
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Seidel, J. V., D. Ehrenreich, R. Allart, H. J. Hoeijmakers, C. Lovis, V. Bourrier, L. Pino, et al. "Into the storm: diving into the winds of the ultra-hot Jupiter WASP-76 b with HARPS and ESPRESSO." Astronomy & Astrophysics 653 (September 2021): A73. http://dx.doi.org/10.1051/0004-6361/202140569.
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Context. Despite swift progress in the characterisation of exoplanet atmospheres in composition and structure, the study of atmospheric dynamics has not progressed at the same speed. While theoretical models have been developed to describe the lower layers of the atmosphere, and independently, the exosphere, little is known about the intermediate layers up to the thermosphere. Aims. We aim to provide a clearer picture of atmospheric dynamics for the class of ultra-hot Jupiters, which are highly irradiated gas giants, based on the example of WASP-76 b. Methods. We jointly analysed two datasets that were obtained with the HARPS and ESPRESSO spectrographs to interpret the resolved planetary sodium doublet. We then applied the MERC code, which retrieves wind patterns, speeds, and temperature profiles on the line shape of the sodium doublet. An updated version of MERC, with added planetary rotation, also provides the possibility of modelling the latitude dependence of the wind patterns. Results. We retrieve the highest Bayesian evidence for an isothermal atmosphere, interpreted as a mean temperature of 3389 ± 227 K, a uniform day- to nightside wind of 5.5−2.0+1.4 km s−1 in the lower atmosphere with a vertical wind in the upper atmosphere of 22.7−4.1+4.9 km s−1, switching atmospheric wind patterns at 10−3 bar above the reference surface pressure (10 bar). Conclusions. Our results for WASP-76 b are compatible with previous studies of the lower atmospheric dynamics of WASP-76 b and other ultra-hot Jupiters. They highlight the need for vertical winds in the intermediate atmosphere above the layers probed by global circulation model studies to explain the line broadening of the sodium doublet in this planet. This work demonstrates the capability of exploiting the resolved spectral line shapes to observationally constrain possible wind patterns in exoplanet atmospheres. This is an invaluable input to more sophisticated 3D atmospheric models in the future.
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Johnstone, C. P., M. Güdel, H. Lammer, and K. G. Kislyakova. "Upper atmospheres of terrestrial planets: Carbon dioxide cooling and the Earth’s thermospheric evolution." Astronomy & Astrophysics 617 (September 2018): A107. http://dx.doi.org/10.1051/0004-6361/201832776.
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Context.The thermal and chemical structures of the upper atmospheres of planets crucially influence losses to space and must be understood to constrain the effects of losses on atmospheric evolution.Aims.We develop a 1D first-principles hydrodynamic atmosphere model that calculates atmospheric thermal and chemical structures for arbitrary planetary parameters, chemical compositions, and stellar inputs. We apply the model to study the reaction of the Earth’s upper atmosphere to large changes in the CO2abundance and to changes in the input solar XUV field due to the Sun’s activity evolution from 3 Gyr in the past to 2.5 Gyr in the future.Methods.For the thermal atmosphere structure, we considered heating from the absorption of stellar X-ray, UV, and IR radiation, heating from exothermic chemical reactions, electron heating from collisions with non-thermal photoelectrons, Joule heating, cooling from IR emission by several species, thermal conduction, and energy exchanges between the neutral, ion, and electron gases. For the chemical structure, we considered ~500 chemical reactions, including 56 photoreactions, eddy and molecular diffusion, and advection. In addition, we calculated the atmospheric structure by solving the hydrodynamic equations. To solve the equations in our model, we developed the Kompot code and have provided detailed descriptions of the numerical methods used in the appendices.Results.We verify our model by calculating the structures of the upper atmospheres of the modern Earth and Venus. By varying the CO2abundances at the lower boundary (65 km) of our Earth model, we show that the atmospheric thermal structure is significantly altered. Increasing the CO2abundances leads to massive reduction in thermospheric temperature, contraction of the atmosphere, and reductions in the ion densities indicating that CO2can significantly influence atmospheric erosion. Our models for the evolution of the Earth’s upper atmosphere indicate that the thermospheric structure has not changed significantly in the last 2 Gyr and is unlikely to change signficantly in the next few Gyr. The largest changes that we see take place between 3 and 2 Gyr ago, with even larger changes expected at even earlier times.
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Loubeau, Alexandra, Victor W. Sparrow, William Doebler, Sriram K. Rallabhandi, Stephane Lemaire, Pierre-Elie Normand, and Sandy R. Liu. "New reference day atmosphere for analyses of quiet supersonic overflight." Journal of the Acoustical Society of America 154, no. 4_supplement (October 1, 2023): A106. http://dx.doi.org/10.1121/10.0022945.
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New reference day atmospheric conditions have been defined for future supersonic aircraft en route noise certification procedures. As field measurements are acquired, in a variety of atmospheric conditions, it is important to relate those measurements back to a common reference atmosphere to provide uniformity in method across applicants for noise certification. Because of the long propagation distances involved between the aircraft flight altitude and the ground, en route noise certification measurements can be substantially affected by the atmosphere. Properties, such as pressure, density, temperature, humidity, and winds, vary with altitude. Therefore, the definition of reference atmospheric profiles as a function of altitude are needed instead of the coarse layered atmosphere and homogeneous humidity used in subsonic aircraft landing and takeoff noise certification. Ground loudness levels from overflight of a quiet supersonic demonstrator concept, calculated with atmospheric data from sites across the world, were compared with the results from several candidate reference atmospheres to identify a reference that would minimize the required adjustment to certification test measurements. The existing ICAO 7488/3 profiles for temperature and pressure, combined with a modified ISO 5878 humidity profile, were found to offer the best results.
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Wunderlich, Fabian, Markus Scheucher, John Lee Grenfell, Franz Schreier, Clara Sousa-Silva, Mareike Godolt, and Heike Rauer. "Detectability of biosignatures on LHS 1140 b." Astronomy & Astrophysics 647 (March 2021): A48. http://dx.doi.org/10.1051/0004-6361/202039663.
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Context. Terrestrial extrasolar planets around low-mass stars are prime targets when searching for atmospheric biosignatures with current and near-future telescopes. The habitable-zone super-Earth LHS 1140 b could hold a hydrogen-dominated atmosphere, and is an excellent candidate for detecting atmospheric features. Aims. In this study we investigate how the instellation and planetary parameters influence the atmospheric climate, chemistry, and spectral appearance of LHS 1140 b. We study the detectability of selected molecules, in particular potential biosignatures, with the upcoming James Webb Space Telescope (JWST) and Extremely Large Telescope (ELT). Methods. In the first step we used the coupled climate–chemistry model 1D-TERRA to simulate a range of assumed atmospheric chemical compositions dominated by molecular hydrogen (H2) and carbon dioxide (CO2). In addition, we varied the concentrations of methane (CH4) by several orders of magnitude. In the second step we calculated transmission spectra of the simulated atmospheres and compared them to recent transit observations. Finally, we determined the observation time required to detect spectral bands with low-resolution spectroscopy using JWST, and the cross-correlation technique using ELT. Results. In H2-dominated and CH4-rich atmospheres oxygen (O2) has strong chemical sinks, leading to low concentrations of O2 and ozone (O3). The potential biosignatures ammonia (NH3), phosphine (PH3), chloromethane (CH3Cl), and nitrous oxide (N2O) are less sensitive to the concentration of H2, CO2, and CH4 in the atmosphere. In the simulated H2-dominated atmosphere the detection of these gases might be feasible within 20 to 100 observation hours with ELT or JWST when assuming weak extinction by hazes. Conclusions. If further observations of LHS 1140 b suggest a thin, clear, hydrogen-dominated atmosphere, the planet would be one of the best known targets to detect biosignature gases in the atmosphere of a habitable-zone rocky exoplanet with upcoming telescopes.
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Chowdhury, Sohini, Yadaiah Nirsanametla, and Muralidhar Manapuram. "Investigation on keyhole mode fiber laser welding of SS 316 in a self-protected atmosphere." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 18 (July 19, 2019): 6602–15. http://dx.doi.org/10.1177/0954406219864137.
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This work focuses on examining the influence of welding parameters under different welding atmospheres and evaluation of keyhole profile during fiber laser welding operation. The experiments are carried out in two different welding atmospheres, namely self-protected atmosphere of Ar gas and open atmospheric conditions. The effect of these two atmospheric conditions on weld profile formation and dimensions, and microstructural evolution for SS 316 plates are examined. In addition, the keyhole profile is evaluated by using a semi-analytical mathematical model, a point-by-point energy balance determination at the keyhole wall, which is mapped with experimentally measured weld macrographs for similar welding conditions. It has been determined that the weld quality is profound in the case of a self-protected atmosphere with respect to aspect ratio, weld defects, and microstructural characterization. Moreover, better weld bead profile and cleaner weld seam on the upper surface is determined in samples welded in a self-protected atmosphere.
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Piette, Anjali A. A., Nikku Madhusudhan, and Avi M. Mandell. "HyDRo: atmospheric retrieval of rocky exoplanets in thermal emission." Monthly Notices of the Royal Astronomical Society 511, no. 2 (December 11, 2021): 2565–84. http://dx.doi.org/10.1093/mnras/stab3612.
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ABSTRACT Emission spectroscopy is a promising technique to observe atmospheres of rocky exoplanets, probing both their chemistry and thermal profiles. We present hydro, an atmospheric retrieval framework for thermal emission spectra of rocky exoplanets. hydro does not make prior assumptions about the background atmospheric composition, and can therefore be used to interpret spectra of secondary atmospheres with unknown compositions. We use hydro to assess the chemical constraints which can be placed on rocky exoplanet atmospheres using JWST. First, we identify the best currently known rocky exoplanet candidates for spectroscopic observations in thermal emission with JWST, finding >30 known rocky exoplanets whose thermal emission will be detectable by JWST/MIRI in fewer than 10 eclipses at R ∼ 10. We then consider the observations required to characterize the atmospheres of three promising rocky exoplanets across the ∼400–800 K equilibrium temperature range: Trappist-1 b, GJ 1132 b, and LHS 3844 b. Considering a range of CO2- to H2O-rich atmospheric compositions, we find that as few as eight eclipses of LHS 3844 b or GJ 1132 b with MIRI LRS will be able to place important constraints on the chemical compositions of their atmospheres. This includes confident detections of CO2 and H2O in the case of a cloud-free CO2-rich composition, besides ruling out a bare rock scenario. Similarly, 30 eclipses of Trappist-1 b with MIRI LRS can allow detections of a cloud-free CO2-rich or CO2-H2O atmosphere. hydro will allow important atmospheric constraints for rocky exoplanets using JWST observations, providing clues about their geochemical environments.
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Romanovskii, Oleg A., and Gennadii G. Matvienko. "Atmospheric and Ocean Optics: Atmospheric Physics." Atmosphere 12, no. 4 (April 8, 2021): 468. http://dx.doi.org/10.3390/atmos12040468.
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Kurosaki, Kenji, and Shu-ichiro Inutsuka. "Giant Impact Events for Protoplanets: Energetics of Atmospheric Erosion by Head-on Collision." Astrophysical Journal 954, no. 2 (September 1, 2023): 196. http://dx.doi.org/10.3847/1538-4357/ace9ba.
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Abstract Numerous exoplanets with masses ranging from Earth to Neptune and radii larger than Earth have been found through observations. These planets possess atmospheres that range in mass fractions from 1% to 30%, reflecting the diversity of atmospheric mass fractions. Such diversities are supposed to be caused by differences in the formation processes or evolution. Here, we consider head-on giant impacts onto planets causing atmosphere losses in the later stage of their formation. We perform smoothed particle hydrodynamic simulations to study the impact-induced atmosphere loss of young super-Earths with 10%–30% initial atmospheric mass fractions. We find that the kinetic energy of the escaping atmosphere is almost proportional to the sum of the kinetic impact energy and self-gravitational energy released from the merged core. We derive the relationship between the kinetic impact energy and the escaping atmosphere mass. The giant impact events for planets of comparable masses are required in the final stage of the popular scenario of rocky planet formation. We show it results in a significant loss of the atmosphere, if the impact is a head-on collision with comparable masses. This latter fact provides a constraint on the formation scenario of rocky planets with substantial atmospheres.
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Medvedev, Alexander S., and Erdal Yiğit. "Gravity Waves in Planetary Atmospheres: Their Effects and Parameterization in Global Circulation Models." Atmosphere 10, no. 9 (September 9, 2019): 531. http://dx.doi.org/10.3390/atmos10090531.
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The dynamical and thermodynamical importance of gravity waves was initially recognized in the atmosphere of Earth. Extensive studies over recent decades demonstrated that gravity waves exist in atmospheres of other planets, similarly play a significant role in the vertical coupling of atmospheric layers and, thus, must be included in numerical general circulation models. Since the spatial scales of gravity waves are smaller than the typical spatial resolution of most models, atmospheric forcing produced by them must be parameterized. This paper presents a review of gravity waves in planetary atmospheres, outlines their main characteristics and forcing mechanisms, and summarizes approaches to capturing gravity wave effects in numerical models. The main goal of this review is to bridge research communities studying atmospheres of Earth and other planets.
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Wogan, Nicholas F., David C. Catling, Kevin J. Zahnle, and Roxana Lupu. "Origin-of-life Molecules in the Atmosphere after Big Impacts on the Early Earth." Planetary Science Journal 4, no. 9 (September 1, 2023): 169. http://dx.doi.org/10.3847/psj/aced83.
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Abstract The origin of life on Earth would benefit from a prebiotic atmosphere that produced nitriles, like HCN, which enable ribonucleotide synthesis. However, geochemical evidence suggests that Hadean air was relatively oxidizing with negligible photochemical production of prebiotic molecules. These paradoxes are resolved by iron-rich asteroid impacts that transiently reduced the entire atmosphere, allowing nitriles to form in subsequent photochemistry. Here we investigate impact-generated reducing atmospheres using new time-dependent, coupled atmospheric chemistry and climate models that account for gas-phase reactions and surface catalysis. The resulting H2-, CH4-, and NH3-rich atmospheres persist for millions of years, until the hydrogen escapes to space. The HCN and HCCCN production and rainout to the surface can reach 109 molecules cm−2 s−1 in hazy atmospheres with a mole ratio of CH4/CO2 > 0.1. Smaller CH4/CO2 ratios produce HCN rainout rates of <105 molecules cm−2 s−1 and negligible HCCCN. The minimum impactor mass that creates atmospheric CH4/CO2 > 0.1 is 4 × 1020–5 × 1021 kg (570–1330 km diameter), depending on how efficiently iron reacts with a steam atmosphere, the extent of atmospheric equilibration with an impact-induced melt pond, and the surface area of nickel that catalyzes CH4 production. Alternatively, if steam permeates and deeply oxidizes the crust, impactors of ∼1020 kg could be effective. Atmospheres with copious nitriles have >360 K surface temperatures, perhaps posing a challenge for RNA longevity, although cloud albedo can produce cooler climates. Regardless, postimpact cyanide can be stockpiled and used in prebiotic schemes after hydrogen has escaped to space.
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Adelson, E. H., and D. C. Somers. "Atmospheric Boundaries in Lightness Perception." Perception 26, no. 1_suppl (August 1997): 60. http://dx.doi.org/10.1068/v970079.
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In judging the lightness of a surface, an observer must estimate and discount the optical viewing conditions: these include illumination level, haze, and interposed filters. The physical effects can be captured in terms of additive and multiplicative factors, which we call ‘atmosphere’. Local atmosphere can be estimated by gathering gray-level statistics over a local window. If the window is too small, the statistics will be impoverished. If the window is too large, it may encompass multiple atmospheres, making the statistics unreliable. We find evidence that the visual system imposes limits on the size and shape of the window, in accord with configural cues that signal atmospheric boundaries. Junctions with proper gray-level arrangements offer powerful cues to atmospheric boundaries; T-, X-, and psi-junctions are especially important. By combining statistics and configural cues, we have generated new lightness illusions that are much stronger than those seen in typical simultaneous-contrast displays. By changing the junctions we can also generate illusions that are quite weak, also in accord with the model.
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Hu, Renyu, Fabrice Gaillard, and Edwin S. Kite. "Narrow Loophole for H2-Dominated Atmospheres on Habitable Rocky Planets around M Dwarfs." Astrophysical Journal Letters 948, no. 2 (May 1, 2023): L20. http://dx.doi.org/10.3847/2041-8213/acd0b4.
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Abstract Habitable rocky planets around M dwarfs that have H2-dominated atmospheres, if they exist, would permit characterizing habitable exoplanets with detailed spectroscopy using JWST, owing to their extended atmospheres and small stars. However, the H2-dominated atmospheres that are consistent with habitable conditions cannot be too massive, and a moderate-sized H2-dominated atmosphere will lose mass to irradiation-driven atmospheric escape on rocky planets around M dwarfs. We evaluate volcanic outgassing and serpentinization as two potential ways to supply H2 and form a steady-state H2-dominated atmosphere. For rocky planets of 1–7 M ⊕ and early-, mid-, and late M-type dwarfs, the expected volcanic outgassing rates from a reduced mantle fall short of the escape rates by > ∼ 1 order of magnitude, and a generous upper limit of the serpentinization rate is still less than the escape rate by a factor of a few. Special mechanisms that may sustain the steady-state H2-dominated atmosphere include direct interaction between liquid water and mantle, heat-pipe volcanism from a reduced mantle, and hydrodynamic escape slowed down by efficient upper-atmospheric cooling. It is thus unlikely to find moderate-size, H2-dominated atmospheres on rocky planets of M dwarfs that would support habitable environments.
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Romanovskii, Oleg A., and Gennadii G. Matvienko. "Atmospheric and Ocean Optics: Atmospheric Physics II." Atmosphere 12, no. 4 (March 26, 2021): 430. http://dx.doi.org/10.3390/atmos12040430.
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Bisikalo, Dmitri, Valery Shematovich, and Benoit Hubert. "The Kinetic Monte Carlo Model of the Auroral Electron Precipitation into N2-O2 Planetary Atmospheres." Universe 8, no. 8 (August 22, 2022): 437. http://dx.doi.org/10.3390/universe8080437.
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Auroral events are the prominent manifestation of solar/stellar forcing on planetary atmospheres. They are closely related to the energy deposition by and evolution of planetary atmospheres, and their observations are widely used to analyze the composition, structure, and chemistry of the atmosphere under study, as well as energy fluxes of the precipitating particles that affect the atmosphere. A numerical kinetic Monte Carlo model had been developed, allowing us to study the processes of precipitation of high-energy auroral electrons into the N2-O2 atmospheres of the rocky planets in the Solar and exosolar planetary systems. This model describes on a molecular level the collisions of auroral electrons and atmospheric gas, taking into account the stochastic nature of collisional scattering at high kinetic energies. The current status of the kinetic model is illustrated in the applications to the auroral events on the Earth such as the production of suprathermal nitrogen atoms due to the electron impact dissociation of N2. It was found that electron impact dissociation of N2 can potentially be an important source of suprathermal N atoms in the auroral regions of the N2-O2 atmosphere of terrestrial-type planets. Such research will allow us to study the odd nitrogen chemistry as an atmospheric marker of the N2-O2 atmosphere of rocky exoplanets.
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Talu, Cigdem. "‘The Effect of London’: Urban Atmospheres and Alice Meynell’s London Impressions." Emotions: History, Culture, Society 6, no. 1 (June 22, 2022): 96–116. http://dx.doi.org/10.1163/2208522x-02010148.
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Abstract This essay examines urban atmospheres and emotions in the 1898 essay collection London Impressions by British writer, poet and suffragist Alice Meynell. I argue atmospheres are spatialised emotions and investigate the atmospheric dimension of Meynell’s text and her impressions, through a vocabulary of immersion and movement. Within her own manipulation of a ‘visual’ vocabulary, Meynell transforms impressions into atmospheres, the visual into sensorial, moving from the painterly to atmospheric experience, notably through the medium of fog and smoke and other climate indicators. I argue urban atmospheres are the main feature the text brings forth (even through – and perhaps especially because of – the filter of the written word). By probing the application of the history of emotions’ methodologies within architectural and urban history, I argue the concept of ‘atmosphere’ is a productive analytical category to examine visual and textual sources.
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Marshak, A., Y. Knyazikhin, J. C. Chiu, and W. J. Wiscombe. "Spectrally Invariant Approximation within Atmospheric Radiative Transfer." Journal of the Atmospheric Sciences 68, no. 12 (December 1, 2011): 3094–111. http://dx.doi.org/10.1175/jas-d-11-060.1.
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Abstract Certain algebraic combinations of single scattering albedo and solar radiation reflected from, or transmitted through, vegetation canopies do not vary with wavelength. These “spectrally invariant relationships” are the consequence of wavelength independence of the extinction coefficient and scattering phase function in vegetation. In general, this wavelength independence does not hold in the atmosphere, but in cloud-dominated atmospheres the total extinction and total scattering phase function vary only weakly with wavelength. This paper identifies the atmospheric conditions under which the spectrally invariant approximation can accurately describe the extinction and scattering properties of cloudy atmospheres. The validity of the assumptions and the accuracy of the approximation are tested with 1D radiative transfer calculations using publicly available radiative transfer models: Discrete Ordinate Radiative Transfer (DISORT) and Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART). It is shown for cloudy atmospheres with cloud optical depth above 3, and for spectral intervals that exclude strong water vapor absorption, that the spectrally invariant relationships found in vegetation canopy radiative transfer are valid to better than 5%. The physics behind this phenomenon, its mathematical basis, and possible applications to remote sensing and climate are discussed.
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Kubát, Jiří. "The sphericity effects in model atmospheres of central stars of Planetary Nebulae." Symposium - International Astronomical Union 180 (1997): 117. http://dx.doi.org/10.1017/s0074180900130037.
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The model atmospheres of central stars of planetary nebulae are often calculated under the assumption of the plane-parallel geometry. This assumption seems to be reasonable for stars with relatively thin atmospheres like white dwarfs, where the thickness of the atmosphere is only few kilometers while the corresponding radius is about several thousands of kilometers. Nevertheless, calculations of a grid of pure hydrogen model atmospheres of hot white dwarfs demonstrated that this assumption may fail even for thin atmospheres (Kubát 1995). We found small differences between line profiles (about 1%) calculated under the assumption of plane-parallel and spherically symmetric atmospheres. Such differences are detectable by contemporary observational technique, and, consequently, may not be neglected. In addition, sphericity effects are important also in stars of other types (Kubát 1996). We decided to test the assumption of the plane parallel geometry also for sample model atmospheres of central stars of planetary nebulae. We assumed static atmospheres in radiative, hydrostatic, and statistical equilibrium (NLTE) consisting of hydrogen and helium. We calculated spherically symmetric and plane parallel model atmospheres of two central stars, namely LoTr4 and K1-27. Basic atmospheric parameters of these stars were adopted from Rauch et al. (1996, 1994), respectively. The atmospheric parameters for LoTr4(Teff = 120000K, log g = 5.5, M = 0.65M⊙, n(H)/n(He) = 0.5 yield a model with an extension (r(τR = 10–5)/r(τR = 2/3)) of 1.028. For K1-27, the atmospheric parameters (Teff = 100000K, log g = 6.5, M = 0.52M⊙, n(H)/n(He) = 0.2 produce only a small extension of 1.0035. The differences in temperature structure of our model atmospheres are more pronounced for a star with lower gravity and, consequently, larger extension. Continuum flux is lower for spherical atmospheres. This difference is larger for LoTr4, i.e. a star with more extended atmosphere, and almost negligible for K1-27. Paschen and Pickering He ii lines also show differences. These differences are quite large (several per cent) for α lines, and they decrease towards higher series members. Using plane-parallel model atmospheres instead of spherically symmetric ones introduces a systematic error into results. This error is present also in highly sophisticated NLTE line blanketed models. Due to the above mentioned differences one should avoid using lower series members (e.g. He ii 4686 å) for determination of atmospheric parameters (Teff, log g, abundances,…) from plane-parallel atmospheres. Details of our calculations will be presented in Astronomy and Astrophysics.
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Turner, Jennifer, Dominique Moran, and Yvonne Jewkes. "‘It's in the air here’: Atmosphere(s) of incarceration." Incarceration 3, no. 3 (August 3, 2022): 263266632211107. http://dx.doi.org/10.1177/26326663221110788.
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Contrary to descriptions of a desensitising situation – with restrictions on movement, monotonous regimes and sparse surroundings – much research highlights imprisonment as sensorially and emotionally powerful. Following work within the ‘turn to affect’ that focuses on non-verbal, non-conscious and, often, non-human embodied experiences, scholars have attended to how such elements cohere into ‘atmospheres’. Whilst the language of atmosphere is synonymous with the prison – a space that is widely anecdotally considered to conjure a particular ‘feeling’ – discussion of the mechanisms for and experiences of atmospheric production and consumption in this space has, thus far, evaded scholarly attention. Atmosphere is a word often used in prison literature, but it is rarely analytically unpacked. Accordingly, drawing on qualitative research data from individuals designing, and working and living in prisons, we focus on how various components – including aesthetics, olfaction, temperature, and the performances that arise from them – comprise sensory atmospheric affects in prison. In doing so, we find atmosphere(s) emerge – not simply from the materiality of the prison itself, but from cultural constructions of carceral and non-carceral landscapes and in conjunction with personal practice and preference. Accordingly, the prison is tied to particular constructions about what a prison should feel like and how people should (re)act to/in such spaces. In some cases, prison designers attempt to engineer particular atmospheres that cohere with wider political motivations around penal philosophies. However, despite the common reflection that prisons generate some kind of atmosphere, respondents are unable to offer a concrete description of what this may be, and much of our data highlights a definite precarity and changeability to atmospheric affect, which is likely to raise ambiguity around attempts to design carceral atmospheres.
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Johnstone, Colin P. "The Influences of Stellar Activity on Planetary Atmospheres." Proceedings of the International Astronomical Union 12, S328 (October 2016): 168–79. http://dx.doi.org/10.1017/s1743921317003775.
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AbstractOn evolutionary timescales, the atmospheres of planets evolve due to interactions with the planet's surface and with the planet's host star. Stellar X-ray and EUV (=’XUV’) radiation is absorbed high in the atmosphere, driving photochemistry, heating the gas, and causing atmospheric expansion and mass loss. Atmospheres can interact strongly with the stellar winds, leading to additional mass loss. In this review, I summarise some of the ways in which stellar output can influence the atmospheres of planets. I will discuss the importance of simultaneously understanding the evolution of the star's output and the time dependent properties of the planet's atmosphere.
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Petricca, Flavio, Antonio Genova, Sander Goossens, Luciano Iess, and Giorgio Spada. "Constraining the Internal Structures of Venus and Mars from the Gravity Response to Atmospheric Loading." Planetary Science Journal 3, no. 7 (July 1, 2022): 164. http://dx.doi.org/10.3847/psj/ac7878.
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Abstract The gravity fields of celestial bodies that possess an atmosphere are periodically perturbed by the redistribution of fluid mass associated with atmospheric dynamics. A component of this perturbation is due to the gravitational response of the body to the deformation of its surface induced by the atmospheric pressure loading. The magnitude of this effect depends on the relation between the loading and the response in terms of geopotential variations measured by the load Love numbers. In this work, we simulate and analyze the gravity field generated by the atmospheres of Venus and Mars by accounting for different models of their internal structure. By precisely characterizing the phenomena that drive the mass transportation in the atmosphere through general circulation models, we determine the effect of the interior structure on the response to the atmospheric loading. An accurate estimation of the time-varying gravity field, which measures the atmospheric contribution, may provide significant constraints on the interior structure through the measurement of the load Love numbers. A combined determination of tidal and load Love numbers would enhance our knowledge of the interior of planetary bodies, providing further geophysical constraints in the inversion of internal structure models.
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Hands, Tom O., and R. Helled. "Super stellar abundances of alkali metals suggest significant migration for hot Jupiters." Monthly Notices of the Royal Astronomical Society 509, no. 1 (October 18, 2021): 894–902. http://dx.doi.org/10.1093/mnras/stab2967.
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ABSTRACT We investigate the origin of the measured overabundance of alkali metals in the atmospheres of hot gas giants, relative to both their host stars and their atmospheric water abundances. We show that formation exterior to the water snow line followed by inward disc-driven migration results in excess accretion of oxygen-poor, refractory-rich material from within the snow-line. This naturally leads to enrichment of alkali metals in the planetary atmosphere relative to the bulk composition of its host star but relative abundances of water that are similar to the stellar host. These relative abundances cannot be explained by in situ formation which places the refractory elements in the planetary deep interior rather than the atmosphere. We therefore suggest that the measured compositions of the atmospheres of hot Jupiters are consistent with significant migration for at least a subset of hot gas giants. Our model makes robust predictions about atmospheric composition that can be confirmed with future data from JWST and Ariel.
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Teng, Chen-Ke-Min, Sheng-Yang Gu, Yusong Qin, and Xiankang Dou. "Impact of Solar Activity on Global Atmospheric Circulation Based on SD-WACCM-X Simulations from 2002 to 2019." Atmosphere 12, no. 11 (November 19, 2021): 1526. http://dx.doi.org/10.3390/atmos12111526.
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In this study, a global atmospheric model, Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension (SD-WACCM-X), and the residual circulation principle were used to study the global atmospheric circulation from the lower to upper atmosphere (~500 km) from 2002 to 2019. Our analysis shows that the atmospheric circulation is clearly influenced by solar activity, especially in the upper atmosphere, which is mainly characterized by an enhanced atmospheric circulation in years with high solar activity. The atmospheric circulation in the upper atmosphere also exhibits an ~11 year period, and its variation is highly correlated with the temporal variation in the F10.7 solar index during the same time series, with a maximum correlation coefficient of up to more than 0.9. In the middle and lower atmosphere, the impact of solar activity on the atmospheric circulation is not as obvious as in the upper atmosphere due to some atmospheric activities such as the Quasi-Biennial Oscillation (QBO), El Niño–Southern Oscillation (ENSO), sudden stratospheric warming (SSW), volcanic forcing, and so on. By comparing the atmospheric circulation in different latitudinal regions between years with high and low solar activity, we found the atmospheric circulation in mid- and high-latitude regions is more affected by solar activity than in low-latitude and equatorial regions. In addition, clear seasonal variation in atmospheric circulation was detected in the global atmosphere, excluding the regions near 10−4 hPa and the lower atmosphere, which is mainly characterized by a flow from the summer hemisphere to the winter hemisphere. In the middle and low atmosphere, the atmospheric circulation shows a quasi-biennial oscillatory variation in the low-latitude and equatorial regions. This work provides a referable study of global atmospheric circulation and demonstrates the impacts of solar activity on global atmospheric circulation.
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Vidotto, A. A., and A. Cleary. "Stellar wind effects on the atmospheres of close-in giants: a possible reduction in escape instead of increased erosion." Monthly Notices of the Royal Astronomical Society 494, no. 2 (April 4, 2020): 2417–28. http://dx.doi.org/10.1093/mnras/staa852.
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ABSTRACT The atmospheres of highly irradiated exoplanets are observed to undergo hydrodynamic escape. However, due to strong pressures, stellar winds can confine planetary atmospheres, reducing their escape. Here, we investigate under which conditions atmospheric escape of close-in giants could be confined by the large pressure of their host star’s winds. For that, we simulate escape in planets at a range of orbital distances ([0.04, 0.14] au), planetary gravities ([36, 87 per cent] of Jupiter’s gravity), and ages ([1, 6.9] Gyr). For each of these simulations, we calculate the ram pressure of these escaping atmospheres and compare them to the expected stellar wind external pressure to determine whether a given atmosphere is confined or not. We show that although younger close-in giants should experience higher levels of atmospheric escape, due to higher stellar irradiation, stellar winds are also stronger at young ages, potentially reducing escape of young exoplanets. Regardless of the age, we also find that there is always a region in our parameter space where atmospheric escape is confined, preferably occurring at higher planetary gravities and orbital distances. We investigate confinement of some known exoplanets and find that the atmosphere of several of them, including π Men c, should be confined by the winds of their host stars, thus potentially preventing escape in highly irradiated planets. Thus, the lack of hydrogen escape recently reported for π Men c could be caused by the stellar wind.
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Meerkötter, R., U. Schumann, D. R. Doelling, P. Minnis, T. Nakajima, and Y. Tsushima. "Radiative forcing by contrails." Annales Geophysicae 17, no. 8 (August 31, 1999): 1080–94. http://dx.doi.org/10.1007/s00585-999-1080-7.
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Abstract. A parametric study of the instantaneous radiative impact of contrails is presented using three different radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treated as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmosphere. The ice water content is varied as a function of ambient temperature. The model atmospheres include tropical, mid-latitude, and subarctic summer and winter atmospheres. Optically thin contrails cause a positive net forcing at top of the atmosphere. At the surface the radiative forcing is negative during daytime. The forcing increases with the optical depth and the amount of contrail cover. At the top of the atmosphere, a mean contrail cover of 0.1% with average optical depth of 0.2 to 0.5 causes about 0.01 to 0.03 Wm-2 daily mean instantaneous radiative forcing. Contrails cool the surface during the day and heat the surface during the night, and hence reduce the daily temperature amplitude. The net effect depends strongly on the daily variation of contrail cloud cover. The indirect radiative forcing due to particle changes in natural cirrus clouds may be of the same magnitude as the direct one due to additional cover.Key words. Atmospheric composition and structure (aerosols and particles) · Meteorology and atmospheric dynamics (climatology · radiative processes)
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Rodríguez-Barrera, M. I., Ch Helling, and K. Wood. "Environmental effects on the ionisation of brown dwarf atmospheres." Astronomy & Astrophysics 618 (October 2018): A107. http://dx.doi.org/10.1051/0004-6361/201832685.
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Context. Brown dwarfs emit bursts of Hα, white-light flares, and show radio flares and quiescent radio emission. They are suggested to form aurorae, similar to planets in the solar system, but much more energetic. All these processes require a source gas with an appropriate degree of ionisation, which, so far, is mostly postulated to be sufficient. Aims. We aim to demonstrate that the Galactic environment influences atmospheric ionisation, and that it hence amplifies or enables the magnetic coupling of the atmospheres of ultra-cool objects, like brown dwarfs and free-floating planets. Methods. We build on our previous work on thermal ionisation of ultra-cool atmospheres and explore the effect of environmental high-energy radiation on the degree of ionisation in the atmosphere. We consider the effect of photoionisation by Lyman-continuum radiation in three different environments: in the interstellar radiation field (ISRF), O and B stars in star-forming regions, and in white dwarf companions in binary systems. We apply our Monte Carlo radiation transfer code to investigate the effect of Lyman-continuum photoionisation for prescribed atmosphere structures for very low-mass objects. Results. The external radiation environment plays an important role for the atmospheric ionisation of very low-mass, ultra-cool objects. Lyman-continuum irradiation greatly increases the level of ionisation in the uppermost atmospheric regions. Our results suggest that a shell of an almost fully ionised atmospheric gas emerges for brown dwarfs in star-forming regions and brown dwarfs in white dwarf binary systems. As a consequence, brown dwarf atmospheres can be magnetically coupled, which is the presumption for chromospheric heating to occur and for aurorae to emerge. First tests for assumed chromosphere-like temperature values suggest that the resulting free-free X-ray luminosities are comparable with those observed from non-accreting brown dwarfs in star-forming regions.
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Ohno, Kazumasa, and Jonathan J. Fortney. "Nitrogen as a Tracer of Giant Planet Formation. I. A Universal Deep Adiabatic Profile and Semianalytical Predictions of Disequilibrium Ammonia Abundances in Warm Exoplanetary Atmospheres." Astrophysical Journal 946, no. 1 (March 1, 2023): 18. http://dx.doi.org/10.3847/1538-4357/acafed.
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Abstract A major motivation of spectroscopic observations of giant exoplanets is to unveil planet formation processes from atmospheric compositions. Several recent studies suggested that atmospheric nitrogen, like carbon and oxygen, can provide important constraints on planetary formation environments. Since nitrogen chemistry can be far from thermochemical equilibrium in warm atmospheres, we extensively investigate under what conditions, and with what assumptions, the observable NH3 abundances can diagnose an atmosphere’s bulk nitrogen abundance. In the first paper of this series, we investigate atmospheric T–P profiles across equilibrium temperature, surface gravity, intrinsic temperature, atmospheric metallicity, and C/O ratio using a 1D radiative–convective equilibrium model. Models with the same intrinsic temperature and surface gravity coincide with a shared “universal” adiabat in the deep atmosphere, across a wide equilibrium temperature range (250–1200 K), which is not seen in hotter or cooler models. We explain this behavior in terms of the classic “radiative zero solution” and then establish a semianalytical T–P profile of the deep atmospheres of warm exoplanets. This profile is then used to predict vertically quenched NH3 abundances. At solar metallicity, our results show that the quenched NH3 abundance only coincides with the bulk nitrogen abundance (within 10%) at low intrinsic temperature, corresponding to a planet with a sub-Jupiter mass (≲1 M J) and old age (≳1 Gyr). If a planet has a high-metallicity (≳10× solar) atmosphere, the quenched NH3 abundance significantly underestimates the bulk nitrogen abundance at almost all planetary masses and ages. We suggest modeling and observational strategies to improve the assessment of bulk nitrogen from NH3.
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Madhusudhan, Nikku, Subhajit Sarkar, Savvas Constantinou, Måns Holmberg, Anjali A. A. Piette, and Julianne I. Moses. "Carbon-bearing Molecules in a Possible Hycean Atmosphere." Astrophysical Journal Letters 956, no. 1 (October 1, 2023): L13. http://dx.doi.org/10.3847/2041-8213/acf577.
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Abstract The search for habitable environments and biomarkers in exoplanetary atmospheres is the holy grail of exoplanet science. The detection of atmospheric signatures of habitable Earth-like exoplanets is challenging owing to their small planet–star size contrast and thin atmospheres with high mean molecular weight. Recently, a new class of habitable exoplanets, called Hycean worlds, has been proposed, defined as temperate ocean-covered worlds with H2-rich atmospheres. Their large sizes and extended atmospheres, compared to rocky planets of the same mass, make Hycean worlds significantly more accessible to atmospheric spectroscopy with JWST. Here we report a transmission spectrum of the candidate Hycean world K2-18 b, observed with the JWST NIRISS and NIRSpec instruments in the 0.9–5.2 μm range. The spectrum reveals strong detections of methane (CH4) and carbon dioxide (CO2) at 5σ and 3σ confidence, respectively, with high volume mixing ratios of ∼1% each in a H2-rich atmosphere. The abundant CH4 and CO2, along with the nondetection of ammonia (NH3), are consistent with chemical predictions for an ocean under a temperate H2-rich atmosphere on K2-18 b. The spectrum also suggests potential signs of dimethyl sulfide (DMS), which has been predicted to be an observable biomarker in Hycean worlds, motivating considerations of possible biological activity on the planet. The detection of CH4 resolves the long-standing missing methane problem for temperate exoplanets and the degeneracy in the atmospheric composition of K2-18 b from previous observations. We discuss possible implications of the findings, open questions, and future observations to explore this new regime in the search for life elsewhere.
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Mukherjee, Sagnick, Jonathan J. Fortney, Caroline V. Morley, Natasha E. Batalha, Mark S. Marley, Theodora Karalidi, Channon Visscher, Roxana Lupu, Richard Freedman, and Ehsan Gharib-Nezhad. "The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios." Astrophysical Journal 963, no. 1 (February 29, 2024): 73. http://dx.doi.org/10.3847/1538-4357/ad18c2.
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Abstract Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain K zz diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for atmospheres with a solar composition. However, atmospheric metallicity and the C/O ratio also impact atmospheric chemistry. Therefore, we present the Sonora Elf Owl grid of self-consistent cloud-free 1D radiative-convective equilibrium model atmospheres for JWST observations, which includes a variation in K zz across several orders of magnitude and also encompasses subsolar to supersolar metallicities and C/O ratios. We find that the impact of K zz on the T(P) profile and spectra is a strong function of both T eff and metallicity. For metal-poor objects, K zz has large impacts on the atmosphere at significantly higher T eff than in metal-rich atmospheres, where the impact of K zz is seen to occur at lower T eff. We identify significant spectral degeneracies between varying K zz and metallicity in multiple wavelength windows, in particular, at 3–5 μm. We use the Sonora Elf Owl atmospheric grid to fit the observed spectra of a sample of nine early to late T-type objects from T eff = 550–1150 K. We find evidence for very inefficient vertical mixing in these objects, with inferred K zz values lying in the range between ∼101 and 104 cm2 s−1. Using self-consistent models, we find that this slow vertical mixing is due to the observations, which probe mixing in the deep detached radiative zone in these atmospheres.
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Lock, Simon J., and Sarah T. Stewart. "Atmospheric Loss in Giant Impacts Depends on Preimpact Surface Conditions." Planetary Science Journal 5, no. 2 (February 1, 2024): 28. http://dx.doi.org/10.3847/psj/ad0b16.
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Abstract Earth likely acquired much of its inventory of volatile elements during the main stage of its formation. Some of Earth’s proto-atmosphere must therefore have survived the giant impacts, collisions between planet-sized bodies, that dominate the latter phases of accretion. Here, we use a suite of 1D hydrodynamic simulations and impedance-match calculations to quantify the effect that preimpact surface conditions (such as atmospheric pressure and the presence of an ocean) have on the efficiency of atmospheric and ocean loss from protoplanets during giant impacts. We find that—in the absence of an ocean—lighter, hotter, and lower-pressure atmospheres are more easily lost. The presence of an ocean can significantly increase the efficiency of atmospheric loss compared to the no-ocean case, with a rapid transition between low- and high-loss regimes as the mass ratio of atmosphere to ocean decreases. However, contrary to previous thinking, the presence of an ocean can also reduce atmospheric loss if the ocean is not sufficiently massive, typically less than a few times the atmospheric mass. Volatile loss due to giant impacts is thus highly sensitive to the surface conditions on the colliding bodies. To allow our results to be combined with 3D impact simulations, we have developed scaling laws that relate loss to the ground velocity and surface conditions. Our results demonstrate that the final volatile budgets of planets are critically dependent on the exact timing and sequence of impacts experienced by their precursor planetary embryos, making atmospheric properties a highly stochastic outcome of accretion.
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Hazra, Gopal, Aline A. Vidotto, Stephen Carolan, Carolina Villarreal D’Angelo, and Ward Manchester. "Effect of stellar flares and coronal mass ejections on the atmospheric escape from hot Jupiters." Proceedings of the International Astronomical Union 17, S370 (August 2021): 148–54. http://dx.doi.org/10.1017/s1743921322004963.
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AbstractSpectral observations in the Ly-α line have shown that atmospheric escape is variable and for the exoplanet HD189733b, the atmospheric evaporation goes from undetected to enhanced evaporation in a 1.5 years interval. To understand the temporal variation in the atmospheric escape, we investigate the effect of flares, winds, and CMEs on the atmosphere of hot Jupiter HD189733b using 3D self-consistent radiation hydrodynamic simulations. We consider four cases: first, the quiescent phase including stellar wind; secondly, a flare; thirdly, a CME; and fourthly, a flare followed by a CME. We find that the flare alone increases the atmospheric escape rate by only 25%, while the CME leads to a factor of 4 increments, in comparison to the quiescent case. We also find that the flare alone cannot explain the observed high blue-shifted velocities seen in the Ly-α. The CME, however, leads to an increase in the velocity of escaping atmospheres, enhancing the blue-shifted transit depth.
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Karabašević, Anđela. "Atmospheric dimensions of architecture." SAJ - Serbian Architectural Journal 8, no. 2 (2016): 179–92. http://dx.doi.org/10.5937/saj1602179k.
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This paper proposes four methodological tools for investigating architectural atmospheres: objective experience, holistic measure, computational simulation and atmospheric visualization. These tools have emerged from a broader PhD research agenda based on the hypothesis that ephemeral effects of light, heat, sound, odor, carried on or in the air, present a scientific basis for precise construction of atmospheres in architecture. By describing my own atmospheric methodology over a series of individual case studies, I will argue that architectural atmospheres can be scientifically investigated and precisely constructed, and that atmospheric approach to architectural research and design offers new invaluable knowledge about the invisible aerial behaviors that determine basic human experience of space.
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Simonetti, Paolo, Giovanni Vladilo, Laura Silva, Michele Maris, Stavro L. Ivanovski, Lorenzo Biasiotti, Matej Malik, and Jost von Hardenberg. "EOS: Atmospheric Radiative Transfer in Habitable Worlds with HELIOS." Astrophysical Journal 925, no. 2 (January 31, 2022): 105. http://dx.doi.org/10.3847/1538-4357/ac32ca.
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Abstract We present EOS, a procedure for determining the outgoing longwave radiation (OLR) and top-of-atmosphere (TOA) albedo for a wide range of conditions expected to be present in the atmospheres of rocky planets with temperate conditions. EOS is based on HELIOS and HELIOS-K, which are novel and publicly available atmospheric radiative transfer (RT) codes optimized for fast calculations with GPU processors. These codes were originally developed for the study of giant planets. In this paper we present an adaptation for applications to terrestrial-type, habitable planets, adding specific physical recipes for the gas opacity and vertical structure of the atmosphere. To test the reliability of the procedure, we assessed the impact of changing line opacity profile, continuum opacity model, atmospheric lapse rate, and tropopause position prescriptions on the OLR and the TOA albedo. The results obtained with EOS are in line with those of other RT codes running on traditional CPU processors, while being at least one order of magnitude faster. The adoption of OLR and TOA albedo data generated with EOS in a zonal and seasonal climate model correctly reproduces the fluxes of the present-day Earth measured by the CERES spacecraft. The results of this study disclose the possibility to incorporate fast RT calculations in climate models aimed at characterizing the atmospheres of habitable exoplanets.
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Smith, Durward, and Joseph D. Norton. "Reduced Atmosphere Storage of Chinese Chestnuts." HortScience 30, no. 4 (July 1995): 890A—890. http://dx.doi.org/10.21273/hortsci.30.4.890a.
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Stored Chinese chestnuts (Castanea molissima Blume) are extremely susceptible to spoilage by molds. This research was initiated to determine if storage at reduced atmospheres in conjunction with vacuum-infused mycostatic chemicals could reduce mold growth and enhance the quality of stored nuts. Nuts were treated with two levels of buffered sodium propionate and two levels of buffered sodium benzoate and stored either at atmospheric pressure or at 0.17 atmosphere (4.0% O2) and minimal gas circulation. Relative humidity was maintained at 88%. Mold counts, weight, texture, and moisture content were recorded every 20 days. Mold counts of the chemically treated nuts stored at atmospheric pressure did not differ from untreated nuts. Storage at reduced atmosphere in conjunction with chemical treatment inhibited mold growth, reduced weight loss, and preserved fresh quality and viability of the nuts.