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Janoo et al. 1998
Janoo, L., Farrugia, C.J., Torbert, R.B., Quinn, J.M., Szabo, A., Lepping, R.P., Ogilvie, K.W., Lin, R.P., Larson, D., Scudder, J.D., Osherovich, V.A. and Steinberg, J.T. (1998). Field and flow perturbations in the October 18–19, 1995, magnetic cloud. Journal of Geophysical Research 103: doi: 10.1029/97JA03173. issn: 0148-0227.

We examine magnetic field and plasma perturbations in the October 18--19, 1995, magnetic cloud. Besides the front boundary, the 3-s-averaged magnetic field measurements made by the Magnetic Field Investigation on the Global Geospace Mission spacecraft Wind reveal a further 15 clear magnetic field directional discontinuities (DDs) with field rotations >15¿, each lasting for ~1 min. A number of these DDs are clustered near the trailing edge of the cloud. Using 3-s resolution proton data from the Three-Dimensional Plasma and Energetic Particle Experiment on Wind, we find that these DDs are accompanied by perturbations in the flow. We find that except for the front boundary, which is a clear tangential discontinuity, all the others are rotational. Across the DDs the bulk flow speed is sometimes enhanced and sometimes depressed. Changes in proton temperature across the DDs suggest a more elaborate structure, for example, a reconnection layer. In a search for large-scale regularities, we apply minimum variance analysis to determine the normals to contiguous 1-hour-long stretches of the cloud data and find that there are large-scale structures ordering the field and the flow for the first 21 hour of cloud data. Thus we identify three coherent segments of several hours' duration each with a well-defined normal, but the normals to the individual segments are very different from each other. In particular, one segment in the cloud Bz0 phase. The normals to the DDs within a given segment are closely aligned with the normal to that segment. For the last 6 hours of cloud data, no coherent structure was found since no reliable normals could be determined. Studying flow anisotropies of electrons in the energy range 0.1--100 keV and changes in intensity in the >1 keV electrons, Larson et al. [1997> inferred several instances of disconnection of cloud field lines from the Sun, which were attributed to reconnection between adjacent bundles of cloud field lines. Our results are supportive of this interpretation. Furthermore, our results suggest the presence of detailed substructure in, and/or large distortions of, the magnetic cloud which reached 1 AU on October 18--19, 1995. ¿ 1998 American Geophysical Union

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Abstract

Keywords
Interplanetary Physics, Discontinuities, Interplanetary Physics, Ejecta, driver gases, and magnetic clouds, Interplanetary Physics, Interplanetary magnetic fields, Interplanetary Physics, Sources of the solar wind
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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