Jupiter’s Mesoscale Waves Observed at 5 μm by Ground-based Observations and Juno JIRAM

Journal
Date Issued
2018
Author(s)
Fletcher, Leigh N.
•
Melin, H.
•
•
Simon, A. A.
•
Sanchez-Lavega, A.
•
Donnelly, P. T.
•
Antuñano, A.
•
Orton, G. S.
•
Hueso, R.
•
Kraaikamp, E.
•
Wong, M. H.
•
Barnett, M.
•
Moriconi, M. L.
•
•
Sindoni, G.
DOI
Abstract
We characterize the origin and evolution of a mesoscale wave pattern in Jupiter’s North Equatorial Belt (NEB), detected for the first time at 5 μm using a 2016-17 campaign of “lucky imaging” from the VISIR instrument on the Very Large Telescope and the NIRI instrument on the Gemini observatory, coupled with M-band imaging from Juno’s JIRAM instrument during the first seven Juno orbits. The wave is compact, with a 1.°1-1.°4 longitude wavelength (wavelength 1300-1600 km, wavenumber 260-330) that is stable over time, with wave crests aligned largely north-south between 14°N and 17°N (planetographic). The waves were initially identified in small (10° longitude) packets immediately west of cyclones in the NEB at 16°N but extended to span wider longitude ranges over time. The waves exhibit a 7-10 K brightness temperature amplitude on top of an ∼210 K background at 5 μm. The thermal structure of the NEB allows for both inertio-gravity waves and gravity waves. Despite detection at 5 μm, this does not necessarily imply a deep location for the waves, and an upper tropospheric aerosol layer near 400-800 mbar could feature a gravity wave pattern modulating the visible-light reflectivity and attenuating the 5-μm radiance originating from deeper levels. Strong rifting activity appears to obliterate the pattern, which can change on timescales of weeks. The NEB underwent a new expansion and contraction episode in 2016-17 with associated cyclone-anticyclone formation, which could explain why the mesoscale wave pattern was more vivid in 2017 than ever before.
Volume
156
Issue
2
Start page
67
Uri
Url
Issn Identifier
0004-6256
Ads BibCode
2018AJ....156...67F
Rights
open.access
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