Summary: Planet. Space Sci. Vol. 29, pp. 215-224
@ Pergamon press Ltd., 1981. Printed in Northern Ireland
THE JOVIAN HYDROGEN BULGE: EVIDENCE FOR CO-ROTATING
Department of Space Physics and Astronomy, Rice University, Houston, TX 77001 U.S.A.
B. R. SANDEL
Earth and Space Sciences Institute, University of Southern California, Tucson, AZ 85713 U.S.A.
S. K. ATREYA
Department of Atmospheric and Oceanic Science, University of Michigan, Ann Arbor, MI 48109 U.S.A.
(Received 29 August 1980)
Abstract-The hydrogen bulge is a feature in Jupiter's upper atmosphere that co-rotates with the
planetary magnetic field (i.e. the hydrogen bulge is fixed in System III coordinates). It is located
approximately 180" removed in System III longitude from the active sector, which has been identified
as the source region for Jovian decametric radio emission and for release of energetic electrons into
interplanetary space. According to the magnetic-anomaly model, the active sector is produced by the
effect of the large magnetic anomaly in Jupiter's northern hemisphere. On the basis of the magnetic-
anomaly model, it has been theoretically expected for some time that a two-cell magnetospheric
convection pattern exists within the Jovian magnetosphere. Because the convection pattern is