A kinematically distorted flux rope model for magnetic clouds

[1] Constant-α force-free magnetic flux rope models have proven to be a valuable first step toward understanding the global context of in situ observations of magnetic clouds. However, cylindrical symmetry is necessarily assumed when using such models, and it is apparent from both observations and modeling that magnetic clouds have highly noncircular cross sections. A number of approaches have been adopted to relax the circular cross section approximation: frequently, the cross-sectional shape is allowed to take an arbitrarily chosen shape (usually elliptical), increasing the number of free parameters that are fit between data and model. While a better “fit” may be achieved in terms of reducing the mean square error between the model and observed magnetic field time series, it is not always clear that this translates to a more accurate reconstruction of the global structure of the magnetic cloud. We develop a new, noncircular cross section flux rope model that is constrained by observations of CMEs/ICMEs and knowledge of the physical processes acting on the magnetic cloud: The magnetic cloud is assumed to initially take the form of a force-free flux rope in the low corona but to be subsequently deformed by a combination of axis-centered self-expansion and heliocentric radial expansion. The resulting analytical solution is validated by fitting to artificial time series produced by numerical MHD simulations of magnetic clouds and shown to accurately reproduce the global structure.

[1]  W. Gonzalez,et al.  The association of coronal mass ejections with their effects near the Earth , 2005 .

[2]  M. Hidalgo.  Correction to “A study of the expansion and distortion of the cross section of magnetic clouds in the interplanetary medium” , 2005 .

[3]  M. Owens,et al.  Non-radial solar wind flows induced by the motion of interplanetary coronal mass ejections , 2004 .

[4]  Q. Hu,et al.  Fitting Flux Ropes to a Global MHD Solution: A Comparison of Techniques. Appendix 1 , 2004 .

[5]  Peter J. Cargill,et al.  On the Aerodynamic Drag Force Acting on Interplanetary Coronal Mass Ejections , 2004 .

[6]  Dusan Odstrcil,et al.  Numerical simulation of the 12 May 1997 interplanetary CME event , 2004 .

[7]  P. Riley,et al.  Kinematic Treatment of Coronal Mass Ejection Evolution in the Solar Wind , 2004 .

[8]  M. Hidalgo.  A study of the expansion and distortion of the cross section of magnetic clouds in the interplanetary medium , 2003 .

[9]  Dusan Odstrcil,et al.  Flux cancellation and coronal mass ejections , 2003 .

[10]  H. Cane,et al.  A survey of interplanetary coronal mass ejections in the near-Earth solar wind during 1996-2002 , 2003 .

[11]  J. Luciani,et al.  Coronal Mass Ejection: Initiation, Magnetic Helicity, and Flux Ropes. I. Boundary Motion-driven Evolution , 2003 .

[12]  C. Russell,et al.  On the magnetosheath thicknesses of interplanetary coronal mass ejections , 2002 .

[13]  C. Russell,et al.  Multispacecraft modeling of the flux rope structure of interplanetary coronal mass ejections: Cylindrically symmetric versus nonsymmetric topologies , 2001 .

[14]  M. Lockwood,et al.  Long‐term changes in the solar photosphere associated with changes in the coronal source flux , 2001 .

[15]  Q. Hu,et al.  Reconstruction of magnetic flux ropes in the solar wind , 2001 .

[16]  Russell A. Howard,et al.  Properties of coronal mass ejections: SOHO LASCO observations from January 1996 to June 1998 , 2000 .

[17]  C. Arge,et al.  Improvement in the prediction of solar wind conditions using near‐real time solar magnetic field updates , 2000 .

[18]  R. Howard,et al.  LASCO and EIT Observations of Helical Structure in Coronal Mass Ejections , 1999 .

[19]  J. Luhmann,et al.  Solar cycle evolution of the structure of magnetic clouds in the inner heliosphere , 1998 .

[20]  S. Antiochos,et al.  A Model for Solar Coronal Mass Ejections , 1998, astro-ph/9807220.

[21]  Jeffrey C. Lagarias,et al.  Convergence Properties of the Nelder-Mead Simplex Method in Low Dimensions , 1998, SIAM J. Optim..

[22]  V. Bothmer,et al.  The structure and origin of magnetic clouds in the solar wind , 1997 .

[23]  James Chen.  Theory of prominence eruption and propagation: Interplanetary consequences , 1996 .

[24]  P. Lamy,et al.  The Large Angle Spectroscopic Coronagraph (LASCO) , 1995 .

[25]  B. Low.  Magnetohydrodynamic processes in the solar corona: Flares, coronal mass ejections, and magnetic helicity* , 1994 .

[26]  D. Rust.  Spawning and Shedding Helical Magnetic Fields in the Solar Atmosphere , 1994 .

[27]  L. Burlaga,et al.  Magnetic field structure of interplanetary magnetic clouds at 1 AU , 1990 .

[28]  L. Burlaga,et al.  Magnetic clouds and force‐free fields with constant alpha , 1988 .

[29]  F. Mariani,et al.  Magnetic loop behind an interplanetary shock: Voyager, Helios and IMP-8 observations , 1981 .

[30]  G. Siscoe,et al.  Characteristic magnetic field and speed properties of interplanetary coronal mass ejections and their sheath regions , 2005 .

[31]  Mathew J. Owens,et al.  Predictions of the arrival time of Coronal Mass Ejections at 1AU: an analysis of the causes of errors , 2004 .

[32]  P. Riley,et al.  Kinematic Treatment of CME Evolution in the Solar Wind , 2004 .

[33]  C. Cid,et al.  A non‐force‐free approach to the topology of magnetic clouds in the solar wind , 2002 .

[34]  L. J. Cahill,et al.  Magnetopause structure and attitude from Explorer 12 observations. , 1967 .

[35]  J. Virginia Lincoln,et al.  Geomagnetic and solar data , 1966 .