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Storms and the Depletion of Ammonia in Jupiter: II. Explaining the Juno Observations

Guillot, Tristan and Li, Cheng and Bolton, Scott J. and Brown, Shannon T. and Ingersoll, Andrew P. and Janssen, Michael A. and Levin, Steven M. and Lunine, Jonathan I. and Orton, Glenn S. and Steffes, Paul G. and Stevenson, David J. (2020) Storms and the Depletion of Ammonia in Jupiter: II. Explaining the Juno Observations. Journal of Geophysical Research. Planets, 125 (8). Art. No. e2020JE006404. ISSN 2169-9097. doi:10.1029/2020je006404.

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Observations of Jupiter's deep atmosphere by the Juno spacecraft have revealed several puzzling facts: The concentration of ammonia is variable down to pressures of tens of bars and is strongly dependent on latitude. While most latitudes exhibit a low abundance, the Equatorial Zone of Jupiter has an abundance of ammonia that is high and nearly uniform with depth. In parallel, the Equatorial Zone is peculiar for its absence of lightning, which is otherwise prevalent most everywhere else on the planet. We show that a model accounting for the presence of small‐scale convection and water storms originating in Jupiter's deep atmosphere accounts for the observations. Where strong thunderstorms are observed on the planet, we estimate that the formation of ammonia‐rich hail (“mushballs”) and subsequent downdrafts can deplete efficiency the upper atmosphere of its ammonia and transport it efficiently to the deeper levels. In the Equatorial Zone, the absence of thunderstorms shows that this process is not occurring, implying that small‐scale convection can maintain a near‐homogeneity of this region. A simple model satisfying mass and energy balance accounts for the main features of Juno's microwave radiometer observations and successfully reproduces the inverse correlation seen between ammonia abundance and the lightning rate as function of latitude. We predict that in regions where ammonia is depleted, water should also be depleted to great depths. The fact that condensates are not well mixed by convection until far deeper than their condensation level has consequences for our understanding of Jupiter's deep interior and of giant‐planet atmospheres in general.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Guillot, Tristan0000-0002-7188-8428
Li, Cheng0000-0002-8280-3119
Bolton, Scott J.0000-0002-9115-0789
Brown, Shannon T.0000-0002-7566-8537
Ingersoll, Andrew P.0000-0002-2035-9198
Janssen, Michael A.0000-0001-5476-731X
Levin, Steven M.0000-0003-2242-5459
Lunine, Jonathan I.0000-0003-2279-4131
Orton, Glenn S.0000-0001-7871-2823
Steffes, Paul G.0000-0003-3962-8957
Stevenson, David J.0000-0001-9432-7159
Additional Information:© 2020 American Geophysical Union. Issue Online: 03 August 2020; Version of Record online: 03 August 2020; Manuscript accepted: 17 April 2020; Manuscript revised: 14 April 2020; Manuscript received: 05 February 2020. This paper is dedicated to the memory of our friend and colleague Adam Showman, curious mind, great scientist, and wonderful man. We thank the two reviewers for their careful reading of the manuscript and constructive comments. T. G. acknowledges support from the Centre National d'Etudes Spatiales and the Japan Society for the Promotion of Science. G. O. was supported by funds from NASA distributed to the Jet Propulsion Laboratory, California Institute of Technology. A. I, J. L., P. S., and D. S. were supported by NASA Contract NNM06AA75C from the Marshall Space Flight Center supporting the Juno Mission Science Team through a subcontract from the Southwest Research Institute. Data Availability Statement: The data used for this article are available online (
Group:Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Southwest Research InstituteUNSPECIFIED
Subject Keywords:Jupiter; atmosphere; composition; meteorology; convection; lightning
Issue or Number:8
Record Number:CaltechAUTHORS:20200819-085457024
Persistent URL:
Official Citation:Guillot, T., Li, C., Bolton, S. J., Brown, S. T., Ingersoll, A. P., Janssen, M. A., et al. (2020). Storms and the depletion of ammonia in Jupiter: II. Explaining the Juno observations. Journal of Geophysical Research: Planets, 125, e2020JE006404.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105021
Deposited By: Tony Diaz
Deposited On:19 Aug 2020 17:28
Last Modified:01 Jun 2023 22:49

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