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The quasiperpendicular environment of large magnetic pulses in Earth's quasiparallel foreshock - ISEE 1 and 2 observationsULF waves in Earth's foreshock cause the instantaneous angle theta-B(n) between the upstream magnetic field and the shock normal to deviate from its average value. Close to the quasi-parallel (Q-parallel) shock, the transverse components of the waves become so large that the orientation of the field to the normal becomes quasi-perpendicular (Q-perpendicular) during applicable phases of each wave cycle. Large upstream pulses of B were observed completely enclosed in excursions of Theta-B(n) into the Q-perpendicular range. A recent numerical simulation included Theta-B(n) among the parameters examined in Q-parallel runs, and described a similar coincidence as intrinsic to a stage in development of the reformation process of such shocks. Thus, the natural environment of the Q-perpendicular section of Earth's bow shock seems to include an identifiable class of enlarged magnetic pulses for which local Q-perpendicular geometry is a necessary association.
Document ID
19930069266
Document Type
Reprint (Version printed in journal)
Authors
Greenstadt, E. W. (NASA Headquarters Washington, DC United States)
Moses, S. L. (NASA Headquarters Washington, DC United States)
Coroniti, F. V. (TRW, Inc. Electromagnetic Technology Dept., Redondo Beach, CA, United States)
Farris, M. H. (NASA Headquarters Washington, DC United States)
Russell, C. T. (California Univ. Los Angeles, United States)
Date Acquired
August 16, 2013
Publication Date
July 23, 1993
Publication Information
Publication: Geophysical Research Letters
Volume: 20
Issue: 14
ISSN: 0094-8276
Subject Category
GEOPHYSICS
Funding Number(s)
CONTRACT_GRANT: NASW-4414
CONTRACT_GRANT: NASW-4749
Distribution Limits
Public
Copyright
Other