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| Titel |
A summary of WIND magnetic clouds for years 1995-2003: model-fitted parameters, associated errors and classifications |
| VerfasserIn |
R. P. Lepping, D. B. Berdichevsky, C.-C. Wu, A. Szabo, T. Narock, F. Mariani, A. J. Lazarus, A. J. Quivers |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 24, no. 1 ; Nr. 24, no. 1 (2006-03-07), S.215-245 |
| Datensatznummer |
250015470
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| Publikation (Nr.) |
 copernicus.org/angeo-24-215-2006.pdf |
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| Zusammenfassung |
| Interplanetary magnetic clouds (MCs) have been identified
for the first 8.6 years of the WIND mission, and their magnetic field
structures have been parameter-fitted by a static, force free,
cylindrically-symmetric model (Lepping et al., 1990) with various levels of
success. This paper summarizes various aspects of the results of the model
fitting by providing: seven estimated model fit-parameter values for each of
the 82 MCs found, their objectively determined quality estimates, closest
approach vectors (in two coordinate frames), fit-parameter errors for the cases of
acceptable quality (50 cases, or 61%), axial magnetic fluxes, axial
current densities, and total axial current - as well as some examples of MC
profiles for various conditions and "categories" for each case (e.g.
Bz: N→S or S→N, etc.). MC quality is estimated from a
quantitative consideration of a large set of parameters, such as the
chi-squared of the model fit, degree of asymmetry of the B profile, and a
comparison of two means of estimating radius. This set of MCs was initially
identified by visual inspection of relevant field and plasma data. Each
resulting MC candidate is then tested through the use of the MC parameter
model, for various adjusted durations to determine the best fit, which
helps to refine the boundary-times. The resulting MC set is called Set 1.
Another, larger, set (Set 2) of MCs is identified through an automated
program whose criteria are based on general MC plasma and field
characteristics at 1AU determined through past experience. Set 1 is almost
fully contained within Set 2, whose frequency of occurrence better matches
that of the sunspot cycle than Set 1. The difference-set (Set 2-Set 1) is
referred to as the magnetic cloud-like (MCL) set, whose members do not very
well represent good flux ropes through modeling. We present a discussion of
how a MC's front boundary is specifically identified in terms of
multi-parameter considerations (i.e. any one or more of: increase in B,
directional discontinuity, magnetic hole in B, drop in proton plasma beta,
B-fluctuation level change, proton temperature drop, etc.), as well as
through the application of the flux rope model. Also presented are examples
of unusual MCs, as well as some commonly occurring relationships, such as
the existence and frequency (approx. 1/2 the time) of upstream interplanetary
shocks, and less frequent internal shocks. |
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