scholarly journals Overcast on Osiris: 3D radiative-hydrodynamical simulations of a cloudy hot Jupiter using the parametrized, phase-equilibrium cloud formation code EddySed

2019 ◽  
Vol 488 (1) ◽  
pp. 1332-1355 ◽  
Author(s):  
S Lines ◽  
N J Mayne ◽  
J Manners ◽  
I A Boutle ◽  
B Drummond ◽  
...  
Keyword(s):  
Phase Equilibrium ◽  
Cloud Model ◽  
Pressure Profile ◽  
Cloud Formation ◽  
Phase Curve ◽  
Radiative Impact ◽  
Cloud Radiative Effects ◽  
Hydrodynamical Simulations ◽  
Cloud Radiative Feedback ◽  
Future Work

ABSTRACT We present results from 3D radiative-hydrodynamical simulations of HD 209458b with a fully coupled treatment of clouds using the EddySed code, critically, including cloud radiative feedback via absorption and scattering. We demonstrate that the thermal and optical structure of the simulated atmosphere is markedly different, for the majority of our simulations, when including cloud radiative effects, suggesting this important mechanism cannot be neglected. Additionally, we further demonstrate that the cloud structure is sensitive to not only the cloud sedimentation efficiency (termed fsed in EddySed), but also the temperature–pressure profile of the deeper atmosphere. We briefly discuss the large difference between the resolved cloud structures of this work, adopting a phase-equilibrium and parametrized cloud model, and our previous work incorporating a cloud microphysical model, although a fairer comparison where, for example, the same list of constituent condensates is included in both treatments is reserved for a future work. Our results underline the importance of further study into the potential condensate size distributions and vertical structures, as both strongly influence the radiative impact of clouds on the atmosphere. Finally, we present synthetic observations from our simulations reporting an improved match, over our previous cloud-free simulations, to the observed transmission, HST WFC3 emission, and 4.5 μm Spitzer phase curve of HD 209458b. Additionally, we find all our cloudy simulations have an apparent albedo consistent with observations.

scholarly journals Can intrinsic alignments of elongated low-mass galaxies be used to map the cosmic web at high redshift?

2019 ◽  
Vol 488 (4) ◽  
pp. 5580-5593 ◽  
Author(s):  
Viraj Pandya ◽  
Joel Primack ◽  
Peter Behroozi ◽  
Avishai Dekel ◽  
Haowen Zhang ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
High Redshift ◽  
Major Axis ◽  
Real Space ◽  
Significant Alignment ◽  
The Galaxy ◽  
Nearby Galaxies ◽  
Low Mass ◽  
Hydrodynamical Simulations ◽  
Future Work

ABSTRACT Hubble Space Telescope observations show that low-mass ($M_*=10^9\!-\!10^{10}\, \mathrm{M}_{\odot }$) galaxies at high redshift (z = 1.0–2.5) tend to be elongated (prolate) rather than disky (oblate) or spheroidal. This is explained in zoom-in cosmological hydrodynamical simulations by the fact that these galaxies are forming in cosmic web filaments where accretion happens preferentially along the direction of elongation. We ask whether the elongated morphology of these galaxies allows them to be used as effective tracers of cosmic web filaments at high redshift via their intrinsic alignments. Using mock light cones and spectroscopically confirmed galaxy pairs from the Cosmic Assembly Near-infared Deep Extragalactic Legacy Survey (CANDELS), we test two types of alignments: (1) between the galaxy major axis and the direction to nearby galaxies of any mass and (2) between the major axes of nearby pairs of low-mass, likely prolate, galaxies. The mock light cones predict strong signals in 3D real space, 3D redshift space, and 2D projected redshift space for both types of alignments (assuming prolate galaxy orientations are the same as those of their host prolate haloes), but we do not detect significant alignment signals in CANDELS observations. However, we show that spectroscopic redshifts have been obtained for only a small fraction of highly elongated galaxies, and accounting for spectroscopic incompleteness and redshift errors significantly degrades the 2D mock signal. This may partly explain the alignment discrepancy and highlights one of several avenues for future work.

scholarly journals First detection of a virial shock with SZ data: implication for the mass accretion rate of Abell 2319

2019 ◽  
Vol 622 ◽  
pp. A136 ◽  
Author(s):  
G. Hurier ◽  
R. Adam ◽  
U. Keshet
Keyword(s):  
Total Mass ◽  
Accretion Rate ◽  
Galaxy Cluster ◽  
Pressure Profile ◽  
Parametric Model ◽  
Large Radius ◽  
The Galaxy ◽  
The Hierarchical Structure ◽  
Shock Location ◽  
Hydrodynamical Simulations

Shocks produced by the accretion of infalling gas in the outskirts of galaxy clusters are expected in the hierarchical structure formation scenario, as found in cosmological hydrodynamical simulations. Here, we report the detection of a shock front at a large radius in the pressure profile of the galaxy cluster A2319 at a significance of 8.6σ, using Planck thermal Sunyaev-Zel’dovich data. The shock is located at (2.93 ± 0.05) × R500 and is not dominated by any preferential radial direction. Using a parametric model of the pressure profile, we derive a lower limit on the Mach number of the infalling gas, ℳ >  3.25 at 95% confidence level. These results are consistent with expectations derived from hydrodynamical simulations. Finally, we use the shock location to constrain the accretion rate of A2319 to Ṁ ≃ (1.4 ± 0.4) × 1014 M⊙ Gyr−1 for a total mass of M200 ≃ 1015 M⊙.

scholarly journals Performance of McRAS-AC in the GEOS-5 AGCM: aerosol-cloud-microphysics, precipitation, cloud radiative effects, and circulation

2012 ◽  
Vol 5 (2) ◽  
pp. 1381-1434 ◽  
Author(s):  
Y. C. Sud ◽  
D. Lee ◽  
L. Oreopoulos ◽  
D. Barahona ◽  
A. Nenes ◽  
...  
Keyword(s):  
Climate Modeling ◽  
Cloud Model ◽  
Cloud Microphysics ◽  
Sensitivity Analyses ◽  
Radiative Effects ◽  
Boundary Layer Clouds ◽  
Aerosol Cloud ◽  
Marine Stratus ◽  
Systematic Biases ◽  
Cloud Radiative Effects

Abstract. A revised version of the Microphysics of clouds with Relaxed Arakawa-Schubert and Aerosol-Cloud interaction scheme (McRAS-AC) including, among others, the Barahona and Nenes ice nucleation parameterization, is implemented in the GEOS-5 AGCM. Various fields from a 10-yr long integration of the AGCM with McRAS-AC were compared with their counterparts from an integration of the baseline GEOS-5 AGCM using satellite data as observations. Generally McRAS-AC simulations have smaller biases in cloud fields and cloud radiative effects over most of the regions of the Earth than the baseline GEOS-5 AGCM. Two systematic biases are identified in the McRAS-AC runs: one under-prediction of cloud particles around 40° S–60° S, and one over-prediction of cloud water path during Northern Hemisphere summer over the Gulf Stream and North Pacific. Sensitivity analyses show that these biases potentially originate from biases in the aerosol input. The first bias is largely eliminated in a sensitivity test using 50% smaller sea-salt aerosol particles, while the second bias is much reduced when interactive aerosol chemistry was turned on. The main drawback of McRAS-AC is dearth of low-level marine stratus clouds, probably due to lack of boundary-layer clouds that is an outcome of explicit dry-convection not yet implemented into the cloud model. Nevertheless, McRAS-AC simulates realistic clouds and their optical properties that can further improve with better aerosol-input. Thereby, McRAS-AC has the potential to be a valuable tool for climate modeling research because of its superior simulation capabilities that physically couple aerosols, cloud microphysics, cloud macrophysics, and cloud-radiation interaction for all clouds.

scholarly journals Molecular cloud formation by compression of magnetized turbulent gas subjected to radiative cooling

2020 ◽  
Vol 493 (3) ◽  
pp. 3098-3113 ◽  
Author(s):  
Ankush Mandal ◽  
Christoph Federrath ◽  
Bastian Körtgen
Keyword(s):  
Molecular Cloud ◽  
Large Scale ◽  
Turnover Rate ◽  
Radiative Heating ◽  
Cloud Formation ◽  
Neutral Medium ◽  
Contraction Rate ◽  
Mhd Turbulence ◽  
Cloud Properties ◽  
Hydrodynamical Simulations

ABSTRACT Complex turbulent motions of magnetized gas are ubiquitous in the interstellar medium (ISM). The source of this turbulence, however, is still poorly understood. Previous work suggests that compression caused by supernova shockwaves, gravity, or cloud collisions, may drive the turbulence to some extent. In this work, we present three-dimensional (3D) magnetohydrodynamic (MHD) simulations of contraction in turbulent, magnetized clouds from the warm neutral medium of the ISM to the formation of cold dense molecular clouds, including radiative heating and cooling. We study different contraction rates and find that observed molecular cloud properties, such as the temperature, density, Mach number, and magnetic field strength, and their respective scaling relations, are best reproduced when the contraction rate equals the turbulent turnover rate. In contrast, if the contraction rate is significantly larger (smaller) than the turnover rate, the compression drives too much (too little) turbulence, producing unrealistic cloud properties. We find that the density probability distribution function evolves from a double lognormal representing the two-phase ISM, to a skewed, single lognormal in the dense, cold phase. For purely hydrodynamical simulations, we find that the effective driving parameter of contracting cloud turbulence is natural to mildly compressive (b ∼ 0.4–0.5), while for MHD turbulence, we find b ∼ 0.3–0.4, i.e. solenoidal to naturally mixed. Overall, the physical properties of the simulated clouds that contract at a rate equal to the turbulent turnover rate, indicate that large-scale contraction may explain the origin and evolution of turbulence in the ISM.

scholarly journals Brown Dwarf Model Atmospheres Based on Multi-Dimensional Radiation Hydrodynamics

2009 ◽  
Vol 5 (H15) ◽  
pp. 756-756 ◽  
Author(s):  
France Allard ◽  
Bernd Freytag
Keyword(s):  
Cloud Model ◽  
Molecular Transport ◽  
Brown Dwarfs ◽  
Model Atmosphere ◽  
Magnetic Activity ◽  
Cloud Formation ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
The Status ◽  
Low Mass

AbstractThe atmospheres of Brown Dwarfs (BDs) are the site of molecular opacities and cloud formation, and control their cooling rate, radius and brightness evolution. Brown dwarfs evolve from stellar-like properties (magnetic activity, spots, flares, mass loss) to planet-like properties (electron degeneracy of the interior, cloud formation, dynamical molecular transport) while retaining, due to their fully convective interior, larger rotational velocities (≤ 30 km/s i.e. P < 4 hrs versus 11 hrs for Jupiter). Model atmospheres treating all this complexity are therefore essential to understand the evolution properties, and to interpret the observations of these objects. While the pure gas-phase based NextGen model atmospheres (Allard et al. 1997, Hauschildt et al. 1999) have allowed the understanding of the several populations of Very Low Mass Stars (VLMs), the AMES-Dusty models (Allard et al. 2001) based on equilibrium chemistry have reproduced some near-IR photometric properties of M and L-type brown dwarfs, and played a key role in the determination of the mass of brown dwarfs and Planetary Mass Objects (PMOs) in the eld and in young stellar clusters. In this paper, we present a new model atmosphere grid for VLMs, BDs, PMOs named BT-Settl, which includes a cloud model and dynamical molecular transport based on mixing information from 2D Radiation Hydrodynamic (RHD) simulations (Freytag et al. 2009). We also present the status of our 3D RHD simulations including rotation (Coriolis forces) of a cube on the surface of a brown dwarf. The BT-Settl model atmosphere grid will be available shortly via the Phoenix web simulator (http://phoenix.ens-lyon.fr/simulator/).

scholarly journals Hydration or dehydration: competing effects of upper tropospheric cloud radiation on the TTL water vapor

2012 ◽  
Vol 12 (2) ◽  
pp. 4655-4678
Author(s):  
L. Wu ◽  
H. Su ◽  
J. H. Jiang ◽  
W. G. Read
Keyword(s):  
Water Vapor ◽  
Wrf Model ◽  
Vertical Motion ◽  
Cloud Formation ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Cloud Radiative Effect ◽  
Adiabatic Cooling ◽  
Cloud Radiative Effects

Abstract. A tropical channel version of the Weather Research and Forecasting (WRF) model is used to investigate the radiative impacts of upper tropospheric clouds on water vapor in the tropical tropopause layer (TTL). The WRF simulations of cloud radiative effects and water vapor in the upper troposphere and lower stratosphere show reasonable agreement with observations, including approximate reproduction of the water vapor "tape recorder" signal. By turning on and off the upper tropospheric cloud radiative effect (UTCRE) above 200 hPa, we find that the UTCRE induces a warming of 0.76 K and a moistening of 9% in the upper troposphere at 215 hPa. However, the UTCRE cools and dehydrates the TTL, with a cooling of 0.82 K and a dehydration of 16% at 100 hPa. The enhanced vertical ascent due to the UTCRE contributes substantially to mass transport and the dehydration in the TTL. The hydration due to the enhanced vertical transport is counteracted by the dehydration from adiabatic cooling associated with the enhanced vertical motion. The UTCRE also substantially changes the horizontal winds in the TTL, resulting in shifts of the strongest dehydration away from the lowest temperature anomalies in the TTL. The UTCRE increases in-situ cloud formation in the TTL. A seasonal variation is shown in the simulated UTCRE, with stronger impact in the moist phase from June to November than in the dry phase from December to May.

scholarly journals An aerosol chamber investigation of the heterogeneous ice nucleating potential of refractory nanoparticles

2010 ◽  
Vol 10 (3) ◽  
pp. 1227-1247 ◽  
Author(s):  
R. W. Saunders ◽  
O. Möhler ◽  
M. Schnaiter ◽  
S. Benz ◽  
R. Wagner ◽  
...  
Keyword(s):  
Silicon Oxide ◽  
Cloud Model ◽  
Active Surface ◽  
Accommodation Coefficient ◽  
Contact Angles ◽  
Nucleation Theory ◽  
Cloud Formation ◽  
Classical Nucleation Theory ◽  
Ice Nuclei

Abstract. Nanoparticles of iron oxide (crystalline and amorphous), silicon oxide and magnesium oxide were investigated for their propensity to nucleate ice over the temperature range 180–250 K, using the AIDA chamber in Karlsruhe, Germany. All samples were observed to initiate ice formation via the deposition mode at threshold ice super-saturations (RHithresh) ranging from 105% to 140% for temperatures below 220 K. Approximately 10% of amorphous Fe2O3 particles (modal diameter = 30 nm) generated in situ from a photochemical aerosol reactor, led to ice nucleation at RHithresh = 140% at an initial chamber temperature of 182 K. Quantitative analysis using a singular hypothesis treatment provided a fitted function [ns(190 K)=10(3.33×sice)+8.16] for the variation in ice-active surface site density (ns:m−2) with ice saturation (sice) for Fe2O3 nanoparticles. This was implemented in an aerosol-cloud model to determine a predicted deposition (mass accommodation) coefficient for water vapour on ice of 0.1 at temperatures appropriate for the upper atmosphere. Classical nucleation theory was used to determine representative contact angles (θ) for the different particle compositions. For the in situ generated Fe2O3 particles, a slight inverse temperature dependence was observed with θ = 10.5° at 182 K, decreasing to 9.0° at 200 K (compared with 10.2° and 11.4° respectively for the SiO2 and MgO particle samples at the higher temperature). These observations indicate that such refractory nanoparticles are relatively efficient materials for the nucleation of ice under the conditions studied in the chamber which correspond to cirrus cloud formation in the upper troposphere. The results also show that Fe2O3 particles do not act as ice nuclei under conditions pertinent for tropospheric mixed phase clouds, which necessarily form above ~233 K. At the lower temperatures (<150 K) where noctilucent clouds form during summer months in the high latitude mesosphere, higher contact angles would be expected, which may reduce the effectiveness of these particles as ice nuclei in this part of the atmosphere.

scholarly journals Development of the Regional Arctic System Model (RASM): Near-Surface Atmospheric Climate Sensitivity

2017 ◽  
Vol 30 (15) ◽  
pp. 5729-5753 ◽  
Author(s):  
John J. Cassano ◽  
Alice DuVivier ◽  
Andrew Roberts ◽  
Mimi Hughes ◽  
Mark Seefeldt ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface ◽  
System Model ◽  
Cold Surface ◽  
Radiative Fluxes ◽  
Near Surface ◽  
Surface Climate ◽  
Radiative Impact ◽  
Future Work

The near-surface climate, including the atmosphere, ocean, sea ice, and land state and fluxes, in the initial version of the Regional Arctic System Model (RASM) are presented. The sensitivity of the RASM near-surface climate to changes in atmosphere, ocean, and sea ice parameters and physics is evaluated in four simulations. The near-surface atmospheric circulation is well simulated in all four RASM simulations but biases in surface temperature are caused by biases in downward surface radiative fluxes. Errors in radiative fluxes are due to biases in simulated clouds with different versions of RASM simulating either too much or too little cloud radiative impact over open ocean regions and all versions simulating too little cloud radiative impact over land areas. Cold surface temperature biases in the central Arctic in winter are likely due to too few or too radiatively thin clouds. The precipitation simulated by RASM is sensitive to changes in evaporation that were linked to sea surface temperature biases. Future work will explore changes in model microphysics aimed at minimizing the cloud and radiation biases identified in this work.

scholarly journals Hydration or dehydration: competing effects of upper tropospheric cloud radiation on the TTL water vapor

2012 ◽  
Vol 12 (16) ◽  
pp. 7727-7735 ◽  
Author(s):  
L. Wu ◽  
H. Su ◽  
J. H. Jiang ◽  
W. G. Read
Keyword(s):  
Water Vapor ◽  
Wrf Model ◽  
Vertical Motion ◽  
Cloud Formation ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Cloud Radiative Effect ◽  
Adiabatic Cooling ◽  
Cloud Radiative Effects

Abstract. A tropical channel version of the Weather Research and Forecasting (WRF) model is used to investigate the radiative impacts of upper tropospheric clouds on water vapor in the tropical tropopause layer (TTL). The WRF simulations of cloud radiative effects and water vapor in the upper troposphere and lower stratosphere show reasonable agreement with observations, including approximate reproduction of the water vapor "tape recorder" signal. By turning on and off the upper tropospheric cloud radiative effect (UTCRE) above 200 hPa, we find that UTCRE induces a warming of 0.76 K and a moistening of 9% in the upper troposphere at 215 hPa. However, UTCRE cools and dehydrates the TTL, with a cooling of 0.82 K and a dehydration of 16% at 100 hPa. The enhanced vertical ascent due to UTCRE contributes substantially to mass transport and the dehydration in the TTL. The hydration due to the enhanced vertical transport is counteracted by the dehydration from adiabatic cooling associated with the enhanced vertical motion. UTCRE also substantially changes the horizontal winds in the TTL, resulting in shifts of the strongest dehydration away from the lowest temperature anomalies in the TTL. UTCRE increases in-situ cloud formation in the TTL. A seasonal variation is shown in the simulated UTCRE, with stronger impact in the moist phase from June to November than in the dry phase from December to May.

scholarly journals Mineral cloud and hydrocarbon haze particles in the atmosphere of the hot Jupiter JWST target WASP-43b

2020 ◽  
Vol 641 ◽  
pp. A178 ◽  
Author(s):  
Ch. Helling ◽  
Y. Kawashima ◽  
V. Graham ◽  
D. Samra ◽  
K. L. Chubb ◽  
...  
Keyword(s):  
Cloud Formation ◽  
Phase Curve ◽  
Hot Jupiters ◽  
Thermodynamic Conditions ◽  
Pressure Scale ◽  
The Mean ◽  
Cloud Particles ◽  
Mean Molecular Weight ◽  
Insight Into

Context. Having a short orbital period and being tidally locked makes WASP-43b an ideal candidate for the James Webb Space Telescope (JWST) phase curve measurements. Phase curve observations of an entire orbit will enable the mapping of the atmospheric structure across the planet, with different wavelengths of observation allowing different atmospheric depths to be seen. Aims. We provide insight into the details of the clouds that may form on WASP-43b and their impact on the remaining gas phase, in order to prepare the forthcoming interpretation of the JWST and follow-up data. Methods. We follow a hierarchical modelling strategy. We utilise 3D GCM results as input for a kinetic, non-equilibrium model for mineral cloud particles and for a kinetic model to study a photochemically-driven hydrocarbon haze component. Results. Mineral condensation seeds form throughout the atmosphere of WASP-43b. This is in stark contrast to the ultra-hot Jupiters, such as WASP-18b and HAT-P-7b. The dayside is not cloud free but it is loaded with few yet large mineral cloud particles in addition to hydrocarbon haze particles of a comparable abundance. Photochemically driven hydrocarbon haze appears on the dayside, but it does not contribute to the cloud formation on the nightside. The geometrical cloud extension differs across the globe due to the changing thermodynamic conditions. Day and night differ by 6000 km in pressure scale height. As reported for other planets, the C/O is not constant throughout the atmosphere and varies between 0.74 and 0.3. The mean molecular weight is approximately constant in a H2-dominated WASP-43b atmosphere because of the moderate day/night-temperature differences compared to the super-hot Jupiters. Conclusions. WASP-43b is expected to be fully covered in clouds which are not homogeneously distributed throughout the atmosphere. The dayside and the terminator clouds are a combination of mineral particles of locally varying size and composition as well as of hydrocarbon hazes. The optical depth of hydrocarbon hazes is considerably lower than that of mineral cloud particles such that a wavelength-dependent radius measurement of WASP-43b would be determined by the mineral cloud particles but not by hazes.

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