The Role of CMEs and Interplanetary Shocks in IMF Statistics and Solar Magnetic Flux Ejection

C. W. Smith and J. L. Phillips

Journal of Geophysical Research, A102, 249-261 (1997)


We examine the role of coronal mass ejections (CMEs) and interplanetary shocks in modifying the large-scale winding of the interplanetary magnetic field (IMF) by extracting CME and shock observations from the ISEE 3 data set and analyzing periods of the disturbed and undisturbed solar wind separately. We use the full ISEE 3 data set representing the entire L1 mission (1978 -- 1982). We conclude that CMEs, the shocks upstream of CMEs, and other interplanetary shocks are responsible for the apparent overwinding of the IMF spiral relative to the Parker prediction. The IMF winding angle asymmetry is preserved following the removal of the interplanetary disturbances. We also examine the IMF components, the IMF magnitude and the solar wind speed, and the dependence of those averages and asymmetries on CMEs and shock disturbances. An estimate is obtained for the anomalous azimuthal field contained within CMEs which apparently results from the closed-field topology. We provide new evidence for a nonzero field component crossing the heliospheric current sheet. Last, we examine the role of CMEs and shocks in the measurement of solar magnetic flux ejection. We provide estimates for the average amount of flux transported by CMEs and the error in flux transport analyses that include shock data, and we examine the possible north-south asymmetry of the flux.

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