Fletcher_2018_AJ_156_67.pdf (3.78 MB)
Jupiter's Mesoscale Waves Observed at 5 mu m by Ground-based Observations and Juno JIRAM
journal contribution
posted on 2018-09-13, 09:13 authored by Leigh N. Fletcher, H. Melin, A. Adriani, A. A. Simon, A. Sanchez-Lavega, P. T. Donnelly, A. Antuñano, G. S. Orton, R. Hueso, E. Kraaikamp, M. H. Wong, M. Barnett, M. L. Moriconi, F. Altieri, G. SindoniWe 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 1fdg1–1fdg4 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.
Funding
Fletcher was supported by a Royal Society Research Fellowship and European Research Council Consolidator Grant (under the European Union's Horizon 2020 research and innovation program, grant agreement No 723890) at the University of Leicester. The UK authors acknowledge the support of the Science and Technology Facilities Council (STFC). Orton was supported by grants from NASA to the Jet Propulsion Laboratory, California Institute of Technology. A. Sanchez-Lavega and R. Hueso were supported by by the Spanish projects AYA2015-65041-P (MINECO/FEDER, UE) and Grupos Gobierno Vasco IT- 765-13. We are grateful to R. Morales-Juberias and R. Cosentino for discussions on the contents of this article. This investigation was based on thermal-infrared observations acquired at the ESO Very Large Telescope Paranal UT3/Melipal Observatory with program IDs 60.A-9620, 098.C-0681. and 099.C-0612. Observations were also obtained at the Gemini Observatory (program ID GN-2017A-Q-60), which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnologa e Innovacin Productiva (Argentina), and Ministrio da Cincia, Tecnologia e Inovao (Brazil). The JIRAM project was founded by the Italian Space Agency (ASI), and we are grateful to all those who participated in the design of these data. The VLT observations are available through the ESO archive,11 and the JIRAM observations are available through the Planetary Data System Atmospheres Node.12 The lucky imaging made use of the Autostakkert software.13 The HST observations are associated with programs GO-14661 and GO-14756, with support provided to Simon, Wong, Barnett, and Orton by NASA through grants from the Space Telescope Science Institute (operated by the Association of Universities for Research in Astronomy
History
Citation
Astronomical Journal, 2018, 156 (2)Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and AstronomyVersion
- VoR (Version of Record)
