Microphysical Prescriptions for Parameterized Water Cloud Formation on Ultra-cool Substellar Objects
arXiv:2408.08958 · doi:10.3847/1538-4357/ad6c4c
Abstract
Water must condense into ice clouds in the coldest brown dwarfs and exoplanets. When they form, these icy clouds change the emergent spectra, temperature structure, and albedo of the substellar atmosphere. The properties of clouds are governed by complex microphysics but these complexities are often not captured by the simpler parameterized cloud models used in climate models or retrieval models. Here, we combine microphysical cloud modeling and 1D climate modeling to incorporate insights from microphysical models into a self-consistent, parameterized cloud model. Using the 1D Community Aerosol and Radiation Model for Atmospheres (CARMA), we generate microphysical water clouds and compare their properties with those from the widely-used EddySed cloud model (Ackerman & Marley 2001) for a grid of Y dwarfs. We find that the mass of water condensate in our CARMA water clouds is significantly limited by available condensation nuclei; in models without additional seed particles for clouds added, the atmosphere becomes supersaturated. We incorporate water latent heat release in the convective and radiative parts of the atmosphere and find no significant impact on water-ice cloud formation for typical gas giant compositions. Our analysis reveals the CARMA cloud profiles have a gradual decrease in opacity of approximately 4% per bar below the cloud base. Incorporating this gradual cloud base falloff and a variable parameter allows spectra generated from the parameterized Eddysed model to better match those of the microphysical CARMA model. This work provides recommendations for efficiently generating microphysically-informed water clouds for future models of cold substellar objects with H/He atmospheres.
15 pages, 19 figures. Published in ApJ
References in corpus (51)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- The NumPy array: a structure for efficient numerical computation
- Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
- Precipitating Condensation Clouds in Substellar Atmospheres
- A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres
- The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
- Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
- Neglected Clouds in T and Y Dwarf Atmospheres
- The Discovery of Y Dwarfs Using Data from the Wide-field Infrared Survey Explorer (WISE)
- Gaseous Mean Opacities for Giant Planet and Ultracool Dwarf Atmospheres over a Range of Metallicities and Temperatures
- A new set of atmosphere and evolution models for cool T-Y brown dwarfs and giant exoplanets
- Masses, Radii, and Cloud Properties of the HR 8799 Planets
- Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars II. Sulfur and Phosphorus
- Comparative Planetary Atmospheres: Models of TrES-1 and HD209458b
- Weather on Other Worlds. II. Survey Results: Spots Are Ubiquitous on L and T Dwarfs
- Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars III. Iron, Magnesium, and Silicon
- Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra
- A Patchy Cloud Model for the L to T Dwarf Transition
- Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
- Water Clouds in Y Dwarfs and Exoplanets
- Exoplanet Reflected Light Spectroscopy with PICASO
- Forward and Inverse Modeling of the Emission and Transmission Spectrum of GJ 436b: Investigating Metal Enrichment, Tidal Heating, and Clouds
- Characterizing 51 Eri b from 1-5 m: a partly-cloudy exoplanet
- Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets
- Sedimentation Efficiency of Condensation Clouds in Substellar Atmospheres
- The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios
- Phase Functions and Light Curves of Wide Separation Extrasolar Giant Planets
- Optical Albedo Theory of Strongly-Irradiated Giant Planets: The Case of HD 209458b
- Observations of Disequilibrium CO Chemistry in the Coldest Brown Dwarfs
- Let the Great World Spin: Revealing the Stormy, Turbulent Nature of Young Giant Exoplanet Analogs with the Spitzer Space Telescope
- Near-infrared photometry of Y dwarfs: low ammonia abundance and the onset of water clouds
- Spectral Variability from the Patchy Atmospheres of T and Y Dwarfs
- Temperature Fluctuations as a Source of Brown Dwarf Variability
- Detection of the nearest Jupiter analog in radial velocity and astrometry data
- The Sonora Substellar Atmosphere Models. II. Cholla: A Grid of Cloud-free, Solar Metallicity Models in Chemical Disequilibrium for the JWST Era
- Patchy Forsterite Clouds in the Atmospheres of Two Highly Variable Exoplanet Analogs
- Developing Atmospheric Retrieval Methods for Direct Imaging Spectroscopy of Gas Giants in Reflected Light I: Methane Abundances and Basic Cloud Properties
- An L Band Spectrum of the Coldest Brown Dwarf
- Probing the Extent of Vertical Mixing in Brown Dwarf Atmospheres with Disequilibrium Chemistry
- The First Spectrum of the Coldest Brown Dwarf
- The First Detection of Photometric Variability in a Y Dwarf: WISE J140518.39+553421.3
- Self-consistent Models of Y Dwarf Atmospheres with Water Clouds and Disequilibrium Chemistry
- Indications of Water Clouds in the Coldest Known Brown Dwarf
- Chemical variation with altitude and longitude on exo-Neptunes: Predictions for Ariel phase-curve observations
- A New Sedimentation Model for Greater Cloud Diversity in Giant Exoplanets and Brown Dwarfs
- Observed Variability at 1um and 4um in the Y0 Brown Dwarf WISEP J173835.52+273258.9
- Uniform Forward-Modeling Analysis of Ultracool Dwarfs. II. Atmospheric Properties of 55 Late-T Dwarfs
- Characterization of Exoplanet Atmospheres with the Optical Coronagraph on WFIRST
- Microphysics of Water Clouds in the Atmospheres of Y Dwarfs and Temperate Giant Planets
- Variable Irradiation on 1D Cloudless Eccentric Exoplanet Atmospheres
- Impacts of Water Latent Heat on the Thermal Structure of Ultra-Cool Objects: Brown Dwarfs and Free-Floating Planets