Skip to content

Constraints on Uranus's haze structure, formation and transport

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalIcarus
Volume333
Early online date24 May 2019
DOIs
DateAccepted/In press - 17 May 2019
DateE-pub ahead of print - 24 May 2019
DatePublished (current) - 15 Nov 2019

Abstract

Microphysical simulations have been performed to constrain the formation and structure of haze in Uranus's atmosphere. These simulations were coupled to a radiative-transfer code to fit observations performed by the SINFONI Integral Field Unit Spectrometer on the Very Large Telescope (VLT)and by the Wide Field Camera 3 (WFC3)of the Hubble Space Telescope (HST)in 2014. Our simulations yield an effective radius of ∼0.2 μm for the haze particles in the tropopause and a density of ∼2.9 particles per cm 3. Our simulations also provide an estimate for the haze production rate in the stratosphere of between ∼3.10 −16 and 3.10 −15 kg m −2 s −1, about 100 times smaller than that found in Titan's atmosphere (e.g. Rannou et al., 2004). This range of values is very similar to that derived by Pollack et al. (1987)from Voyager-2 observations in 1986, suggesting microphysical timescales greater than the elapsed time between these observations (28 years, or 1/3 of a Uranian year). This result is in agreement with analyses performed with our microphysical model that show timescales for haze particles to grow and settle out to be >∼30 years at pressure levels >0.1 bar. However, these timescales are too big to explain the observed variations in the haze structure over Uranus's northern hemisphere after 2007 equinox (e.g. de Pater et al., 2015). This indicates that dynamics may be the main factor controlling the spatial and temporal distribution of the haze over the poles. A meridional stratospheric transport of haze particles with winds velocities >∼0.025 m s −1 would result in dynamics timescales shorter than 30 years and thus may explain the observed variations in the haze structure.

    Research areas

  • Haze microphysics, Radiative transfer, Uranus

Download statistics

No data available

Documents

Documents

  • Full-text PDF (final published version)

    Rights statement: This is the final published version of the article (version of record). It first appeared online via Elsevier at https://doi.org/10.1016/j.icarus.2019.05.018 . Please refer to any applicable terms of use of the publisher.

    Final published version, 1 MB, PDF document

    Licence: CC BY

DOI

View research connections

Related faculties, schools or groups