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Longitudinal Variation and Waves in Jupiter's South Equatorial Wind JetA detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5 S planetographic latitude shows variations in velocity with longitude and time. The presence of the large anticyclonic South Equatorial Disturbance (SED) has a profound effect on the chevron velocity, causing slower velocities to its east and accelerations over distance from the disturbance. The chevrons move with velocities near the maximum wind jet velocity of approx 140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 N latitude. Their repetitive nature is consistent with a gravity-inertia wave (n = 75 to 100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, for the first time, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a 6.7 +/- 0.7-day period. This oscillating motion has a wavelength of approx 20 and a speed of 101 +/- 3 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it. All dates show chevron latitude variability, but it is unclear if this larger wave is present during other epochs, as there are no other suitable time series movies that fully delineate it. In the presence of mUltiple wave modes, the difference in dominant cloud appearance between 7 deg N and 7.5 deg S is likely due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.
Document ID
20120011637
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Simon-Miller, Amy A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Choi, David
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rogers, John H.
(British Astronomical Association London, United Kingdom)
Gierasch, Peter J.
(Cornell Univ. Ithaca, NY, United States)
Allison, Michael D.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Adamoli, Gianluigi
(British Astronomical Association London, United Kingdom)
Mettig, Hans-Joerg
(British Astronomical Association London, United Kingdom)
Date Acquired
August 26, 2013
Publication Date
January 1, 2012
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
GSFC.JA.5898.2012
Funding Number(s)
CONTRACT_GRANT: NAS5-26555
Distribution Limits
Public
Copyright
Public Use Permitted.
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