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Small lightning flashes from shallow electrical storms on Jupiter

Becker, Heidi N. and Alexander, James W. and Atreya, Sushil K. and Bolton, Scott J. and Brennan, Martin J. and Brown, Shannon T. and Guillaume, Alexandre and Guillot, Tristan and Ingersoll, Andrew P. and Levin, Steven M. and Lunine, Jonathan I. and Aglyamov, Yury S. and Steffes, Paul G. (2020) Small lightning flashes from shallow electrical storms on Jupiter. Nature, 584 (7919). pp. 55-58. ISSN 0028-0836. https://resolver.caltech.edu/CaltechAUTHORS:20200327-111725846

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[img] MS Excel (Supplementary Data 3) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 1: Properties of the SRU optical system) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 2: Overlap of the beam of MWR antenna 1 and the SRU field of view during lightning detections) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 3: Estimated spatial extent of flashes) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 6: Reconstruction of the true profile of a flash) - Supplemental Material
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[img] Image (JPEG) (Extended Data Fig. 7: Maximum durations of flashes observed with no TDI) - Supplemental Material
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[img] Image (JPEG) (Extended Data Table 1: Lightning flashes observed by the Juno SRU) - Supplemental Material
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Abstract

Lightning flashes have been observed by a number of missions that visited or flew by Jupiter over the past several decades. Imagery led to a flash rate estimate of about 4 × 10⁻³ flashes per square kilometre per year (refs. 1,2). The spatial extent of Voyager flashes was estimated to be about 30 kilometres (half-width at half-maximum intensity, HWHM), but the camera was unlikely to have detected the dim outer edges of the flashes, given its weak response to the brightest spectral line of Jovian lightning emission, the 656.3-nanometre Hα line of atomic hydrogen. The spatial resolution of some cameras allowed investigators to confirm 22 flashes with HWHM greater than 42 kilometres, and to estimate one with an HWHM of 37 to 45 kilometres (refs. 1,7,8,9). These flashes, with optical energies comparable to terrestrial ‘superbolts’—of (0.02–1.6) × 10¹⁰ joules—have been interpreted as tracers of moist convection originating near the 5-bar level of Jupiter’s atmosphere (assuming photon scattering from points beneath the clouds). Previous observations of lightning have been limited by camera sensitivity, distance from Jupiter and long exposures (about 680 milliseconds to 85 seconds), meaning that some measurements were probably superimposed flashes reported as one. Here we report optical observations of lightning flashes by the Juno spacecraft with energies of approximately 10⁵–10⁸ joules, flash durations as short as 5.4 milliseconds and inter-flash separations of tens of milliseconds, with typical terrestrial energies. The flash rate is about 6.1 × 10⁻² flashes per square kilometre per year, more than an order of magnitude greater than hitherto seen. Several flashes are of such small spatial extent that they must originate above the 2-bar level, where there is no liquid water. This implies that multiple mechanisms for generating lightning on Jupiter need to be considered for a full understanding of the planet’s atmospheric convection and composition.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1038/s41586-020-2532-1DOIArticle
https://rdcu.be/b550CPublisherFree ReadCube access
ORCID:
AuthorORCID
Atreya, Sushil K.0000-0002-1972-1815
Bolton, Scott J.0000-0002-9115-0789
Brown, Shannon T.0000-0002-7566-8537
Guillot, Tristan0000-0002-7188-8428
Ingersoll, Andrew P.0000-0002-2035-9198
Levin, Steven M.0000-0003-2242-5459
Lunine, Jonathan I.0000-0003-2279-4131
Steffes, Paul G.0000-0003-3962-8957
Additional Information:© 2020 Springer Nature Limited. Received 26 August 2019; Accepted 09 April 2020; Published 05 August 2020. We thank G. Berrighi and S. Becucci of the Leonardo Finmeccanica S.p.A. (formerly Selex Galileo S.p.A) Juno SRU Team for retrieval of SRU optics and CCD quantum efficiency parameters used in the study. We thank J. E. P. Connerney for comments on the manuscript. J. Arballo is thanked for rendering of figures and tables. M. Stetson is thanked for artistic rendering of Fig. 3. We thank Y. Yair for bringing the consideration of ice–ice collision charge separation to our attention. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration; at the Observatoire de la Côte d’Azur under the sponsorship of the Centre National d’Etudes Spatiales; and at the Southwest Research Institute under contract with NASA. Data availability: The Juno SRU data supporting the findings of this study are available within the paper and its Supplementary Information. The Juno MWR data that support the findings of this study are available from the Planetary Data System archive (https://pds.nasa.gov/index.shtml) as ‘Juno Jupiter MWR reduced data records v1.0’ (dataset JNO-J-MWR-3-RDR-V1.0). Source data are provided with this paper. Author Contributions: H.N.B. led the acquisition and interpretation of SRU lightning data, wrote the manuscript with input from co-authors, and performed the SRU camera response computations. S.J.B. and T.G. contributed to the interpretation of shallow lightning atmospheric dynamics. M.J.B. contributed to the acquisition of SRU lighting data and performed the SRU observation geometry computations. J.W.A. contributed to SRU camera response computations, flash identification and mapping, and analysis of camera vignetting characteristics. A.G. computed the SRU survey area. S.K.A. and P.G.S. contributed expertise in Jovian atmospheric dynamics and composition. J.I.L. assisted with the ammonia-water thermodynamics, the lightning generation discussion and construction of Fig. 3. Y.S.A. contributed to the lightning generation discussion. A.P.I. contributed to the SRU data interpretation. S.T.B. analysed the MWR data to extract and filter MWR lighting observations. S.M.L. is the lead co-investigator of the MWR. The authors declare no competing interests.
Funders:
Funding AgencyGrant Number
NASA/JPL/CaltechUNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Southwest Research InstituteUNSPECIFIED
Issue or Number:7919
Record Number:CaltechAUTHORS:20200327-111725846
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200327-111725846
Official Citation:Becker, H.N., Alexander, J.W., Atreya, S.K. et al. Small lightning flashes from shallow electrical storms on Jupiter. Nature 584, 55–58 (2020). https://doi.org/10.1038/s41586-020-2532-1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102143
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:02 Apr 2020 15:03
Last Modified:17 Aug 2020 20:36

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