CME-Driven Solar Wind Disturbances Far From the Sun and at High Latitudes

John T. Gosling

Abstract

Ulysses has observed a large number of CME-driven solar wind disturbances during the rise of the present solar activity cycle.  Indeed, the number of transient events identified in the Ulysses data set far exceeds that previously identified at large distances in the Pioneer 10 and 11 and Voyager 1 and 2 data sets.  These disturbances are usually best identified by counterstreaming fluxes of suprathermal electrons in pitch angle plots of the Ulysses plasma data.  The prevalence of counterstreaming indicates that even at large heliocentric distances a large fraction of the magnetic field lines threading most CMEs are rooted at both ends in the solar corona.  Most CMEs at large distances have distinct magnetic field signatures, although these signatures vary from event to event and one often can not identify a CME on the basis of the field signature alone.  Most of the CMEs do not fit the standard definition of magnetic clouds, although some magnetic clouds are clearly present in the data.  A number of the CMEs drive shock wave disturbances, but at large distances the shocks usually are relatively weak, and most CME-driven disturbances at distances of 3-5 AU do not provide large perturbations to the solar wind speed.  Many of the CMEs at large distances have very large spatial extents owing to their expansion en route from the Sun.  Here we provide an overview of these disturbances as identified by the solar wind plasma and magnetic field experiments on Ulysses.

   Authors: J. T. Gosling, D. J. McComas, R. M. Skoug, and R. J. Forsyth

  Organization: Los Alamos National Laboratory
     Telephone: 505-667-5389
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        e-mail: jgosling@lanl.gov
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