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J.T. Clarke (Boston University), D. Grodent Collaboration, J. Connerney Collaboration
Repeated imaging of Jupiterís aurora has shown that the northern main oval has a distorted ďkidney beanĒ shape in the general range of 40-100 deg magnetic longitude, which appears unchanged since 1994. More recently, improved accuracy in locating the satellite footprint auroral emissions has provided new information about the geometry of Jupiterís magnetic field in this and other areas. The persistent pattern of the main oval implies a disturbance of the local magnetic field, and the increased latitudinal separation of the locus of satellite footprints from each other and from the main oval implies a locally weaker field strength. It is possible that these phenomena result from a magnetic anomaly in Jupiterís intrinsic magnetic field, as was proposed by A. Dessler in the 1970ís. There is presently only limited evidence from the scarcity of auroral footprints observed in this longitude range. Similarly, while it is difficult to observe the conjugate regions in the southern aurora, there does not appear to be any corresponding distortion in the south. We will present the observational evidence that we have accumulated to date, propose future observations to determine the nature of this disturbance, and speculate on its causes and implications.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.