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dc.contributor.authorTan, Xianyu
dc.contributor.authorShowman, Adam P.
dc.date.accessioned2017-07-06T22:59:49Z
dc.date.available2017-07-06T22:59:49Z
dc.date.issued2017-01-30
dc.identifier.citationEffects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets 2017, 835 (2):186 The Astrophysical Journalen
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/1538-4357/835/2/186
dc.identifier.urihttp://hdl.handle.net/10150/624643
dc.description.abstractThe growing number of observations of brown dwarfs (BDs) has provided evidence for strong atmospheric circulation on these objects. Directly imaged planets share similar observations and can be viewed as low-gravity versions of BDs. Vigorous condensate cycles of chemical species in their atmospheres are inferred by observations and theoretical studies, and latent heating associated with condensation is expected to be important in shaping atmospheric circulation and influencing cloud patchiness. We present a qualitative description of the mechanisms by which condensational latent heating influences circulation, and then illustrate them using an idealized general circulation model that includes a condensation cycle of silicates with latent heating and molecular weight effect due to the rainout of the condensate. Simulations with conditions appropriate for typical T dwarfs exhibit the development of localized storms and east-west jets. The storms are spatially inhomogeneous, evolving on a timescale of hours to days and extending vertically from the condensation level to the tropopause. The fractional area of the BD covered by active storms is small. Based on a simple analytic model, we quantitatively explain the area fraction of moist plumes and show its dependence on the radiative timescale and convective available potential energy (CAPE). We predict that if latent heating dominates cloud formation processes, the fractional coverage area of clouds decreases as the spectral type goes through the L/T transition from high to lower effective temperature. This is a natural consequence of the variation of the radiative timescale and CAPE with the spectral type.
dc.description.sponsorshipNASA Headquarters; NSF [AST 1313444]en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/0004-637X/835/i=2/a=186?key=crossref.f25d934647027d830dc12e90bf85b348en
dc.rights© 2017. The American Astronomical Society. All rights reserved.en
dc.subjectbrown dwarfsen
dc.subjecthydrodynamicsen
dc.subjectmethods: numericalen
dc.subjectplanets and satellites: atmospheres planetsen
dc.subjectplanets and satellites: gaseous planetsen
dc.titleEffects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planetsen
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Dept Planetary Scien
dc.contributor.departmentUniv Arizona, Lunar & Planetary Laben
dc.identifier.journalThe Astrophysical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-04-26T07:56:16Z
html.description.abstractThe growing number of observations of brown dwarfs (BDs) has provided evidence for strong atmospheric circulation on these objects. Directly imaged planets share similar observations and can be viewed as low-gravity versions of BDs. Vigorous condensate cycles of chemical species in their atmospheres are inferred by observations and theoretical studies, and latent heating associated with condensation is expected to be important in shaping atmospheric circulation and influencing cloud patchiness. We present a qualitative description of the mechanisms by which condensational latent heating influences circulation, and then illustrate them using an idealized general circulation model that includes a condensation cycle of silicates with latent heating and molecular weight effect due to the rainout of the condensate. Simulations with conditions appropriate for typical T dwarfs exhibit the development of localized storms and east-west jets. The storms are spatially inhomogeneous, evolving on a timescale of hours to days and extending vertically from the condensation level to the tropopause. The fractional area of the BD covered by active storms is small. Based on a simple analytic model, we quantitatively explain the area fraction of moist plumes and show its dependence on the radiative timescale and convective available potential energy (CAPE). We predict that if latent heating dominates cloud formation processes, the fractional coverage area of clouds decreases as the spectral type goes through the L/T transition from high to lower effective temperature. This is a natural consequence of the variation of the radiative timescale and CAPE with the spectral type.


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