Several recent studies suggest that magnetic reconnection is able to erode substantial amounts of the outer magnetic flux of interplanetary magnetic clouds (MCs) as they propagate in the heliosphere. We quantify and provide a broader context to this process, starting from 263 tabulated interplanetary coronal mass ejections, including MCs, observed over a time period covering 17years and at a distance of 1AU from the Sun with Wind (1995-2008) and the two STEREO (2009-2012) spacecraft. Based on several quality factors, including careful determination of the MC boundaries and main magnetic flux rope axes, an analysis of the azimuthal flux imbalance expected from erosion by magnetic reconnection was performed on a subset of 50 MCs. The results suggest that MCs may be eroded at the front or at rear and in similar proportions, with a significant average erosion of about 40% of the total azimuthal magnetic flux. We also searched for in situ signatures of magnetic reconnection causing erosion at the front and rear boundaries of these MCs. Nearly ~30% of the selected MC boundaries show reconnection signatures. Given that observations were acquired only at 1AU and that MCs are large-scale structures, this finding is also consistent with the idea that erosion is a common process. Finally, we studied potential correlations between the amount of eroded azimuthal magnetic flux and various parameters such as local magnetic shear, Alfvén speed, and leading and trailing ambient solar wind speeds. However, no significant correlations were found, suggesting that the locally observed parameters at 1AU are not likely to be representative of the conditions that prevailed during the erosion which occurred during propagation from the Sun to 1AU. Future heliospheric missions, and in particular Solar Orbiter or Solar Probe Plus, will be fully geared to answer such questions. ©2014. American Geophysical Union.
Documento: | Artículo |
Título: | Statistical study of magnetic cloud erosion by magnetic reconnection |
Autor: | Ruffenach, A.; Lavraud, B.; Farrugia, C.J.; Démoulin, P.; Dasso, S.; Owens, M.J.; Sauvaud, J.-A.; Rouillard, A.P.; Lynnyk, A.; Foullon, C.; Savani, N.P.; Luhmann, J.G.; Galvin, A.B. |
Filiación: | Institut de Recherche en Astrophysique et Planétologie Université de Toulouse Toulouse France Centre National de la Recherche Scientifique, UMR Toulouse France Space Science Center University of New Hampshire Durham, New Hampshire USA Observatoire de Paris, LESIA, UMR 8109 CNRS Meudon France Instituto de Astronomía y Física del Espacio Buenos Aires Argentina Departamento de Ciencias de la Atmósfera y los Océanos and Departamento de Física, Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires Buenos Aires Argentina Space Environment Physics Group University of Reading Reading, Berkshire UK EMPS/CGAFD University of Exeter Exeter UK School of Physics, Astronomy and Computational Sciences George Mason University Fairfax, Virginia USA NASA Goddard Greenbelt, Maryland USA Space Sciences Laboratory University of California Berkeley, California USA |
Palabras clave: | Coronal mass ejection; Magnetic cloud; Magnetic flux rope; Magnetic reconnection; Solar wind |
Año: | 2015 |
DOI: | http://dx.doi.org/10.1002/2014JA020628 |
Título revista: | Journal of Geophysical Research A: Space Physics |
Título revista abreviado: | J. Geophys. Res. A. Space Phys. |
ISSN: | 21699380 |
Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_21699380_v_n_p_Ruffenach |