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Jupiter’s Temperate Belt/Zone Contrasts Revealed at Depth by Juno Microwave Observations
  • +12
  • Leigh N Fletcher,
  • Fabiano A Oyafuso,
  • Michael D Allison,
  • Andrew Ingersoll,
  • Liming Li,
  • Yohai Kaspi,
  • Eli Galanti,
  • Mike H Wong,
  • Glenn S Orton,
  • Keren Duer,
  • Zhimeng Zhang,
  • Cheng Li,
  • Tristan Guillot,
  • Steven M. Levin,
  • Scott J Bolton
Leigh N Fletcher
University of Leicester, University of Leicester

Corresponding Author:leigh.fletcher@le.ac.uk

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Fabiano A Oyafuso
Jet Propulsion Laboratory, Jet Propulsion Laboratory
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Michael D Allison
Goddard Institute for Space Studies, Goddard Institute for Space Studies
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Andrew Ingersoll
Caltech, Caltech
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Liming Li
University of Houston, University of Houston
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Yohai Kaspi
Weizmann Institute of Science, Weizmann Institute of Science
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Eli Galanti
Weizmann Institute of Science, Weizmann Institute of Science
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Mike H Wong
SETI Institute, SETI Institute
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Glenn S Orton
Jet Propulsion Laboratory, California Institute of Technology, Jet Propulsion Laboratory, California Institute of Technology
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Keren Duer
Weizmann Institute of Science, Weizmann Institute of Science
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Zhimeng Zhang
California Institute of Technology, California Institute of Technology
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Cheng Li
University of Michigan, University of Michigan
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Tristan Guillot
Observatoire de la Cote d'Azur, Observatoire de la Cote d'Azur
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Steven M. Levin
Jet Propulsion Laboratory, Jet Propulsion Laboratory
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Scott J Bolton
Southwest Research Institute, Southwest Research Institute
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Abstract

Juno microwave radiometer (MWR) observations of Jupiter’s mid-latitudes reveal a strong correlation between brightness temperature contrasts and zonal winds, confirming that the banded structure extends throughout the troposphere. However, the microwave brightness gradient is observed to change sign with depth: the belts are microwave-bright in the p< bar range and microwave-dark in the p>10 bar range. The transition level (which we call the jovicline) is evident in the MWR 11.5 cm channel, which samples the 5-14 bar range when using the limb-darkening at all emission angles. The transition is located between 4 and 10 bars, and implies that belts change with depth from being NH3-depleted to NH3-enriched, or from physically-warm to physically-cool, or more likely a combination of both. The change in character occurs near the statically stable layer associated with water condensation. The implications of the transition are discussed in terms of ammonia redistribution via meridional circulation cells with opposing flows above and below the water condensation layer, and in terms of the ‘mushball’ precipitation model, which predicts steeper vertical ammonia gradients in the belts versus the zones. We show via the moist thermal wind equation that both the temperature and ammonia interpretations can lead to vertical shear on the zonal winds, but the shear is ~50x weaker if only NH3 gradients are considered. Conversely, if MWR observations are associated with kinetic temperature gradients then it would produce zonal winds that increase in strength down to the jovicline, consistent with Galileo probe measurements; then decay slowly at higher pressures.
Oct 2021Published in Journal of Geophysical Research: Planets volume 126 issue 10. 10.1029/2021JE006858