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Published November 2018 | Published
Journal Article Open

Characterization of Mesoscale Waves in the Jupiter NEB by Jupiter InfraRed Auroral Mapper on board Juno

Abstract

In 2017, the Jupiter InfraRed Auroral Mapper (JIRAM), on board the NASA-ASI Juno mission, observed a wide longitude region (50° W–80° E in System III) that was perturbed by a wave pattern centered at 15° N in the Jupiter's North Equatorial Belt (NEB). We analyzed JIRAM data acquired on 2017 July 10 using the M-channel and on 2017 February 2 with the spectrometer. The two observations occurred at different times and at slightly different latitudes. The waves appear as clouds blocking the deeper thermal emission. The wave crests are oriented north–south, and the typical wave packet contains 10 crests and 10 troughs. We used Fourier analysis to rigorously determine the wavenumbers associated with the observed patterns at a confidence level of 90%. Wavelet analysis was also used to constrain the spatial localization of the largest energies involved in the process and determine the wavelengths carrying the major contribution. We found wavelengths ranging from 1400 to 1900 km, and generally decreasing toward the west. Where possible, we also computed a vertical location of the cloud pressure levels from the inversion of the spectral radiances measured by the JIRAM spectrometer. The waves were detected at pressure levels consistent with the NH3 as well as NH4SH clouds. Phase velocities could not be determined with sufficient confidence to discriminate whether the alternating crests and troughs are a propagating wave or a manifestation of a fluid dynamical instability.

Additional Information

© 2018 The American Astronomical Society. Received 2018 May 16; revised 2018 September 18; accepted 2018 September 26; published 2018 November 2. The JIRAM project is funded by the Italian Space Agency (ASI). In particular, this work has been developed under the ASI-INAF agreement n. 2016-23-H.0. A portion of this work was funded by NASA through the Juno mission, a portion of which was distributed to the Jet Propulsion Laboratory, California Institute of Technology.

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August 19, 2023
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October 19, 2023