scholarly journals Two-spacecraft reconstruction of a magnetic cloud and comparison to its solar source

2008 ◽  
Vol 26 (10) ◽  
pp. 3139-3152 ◽  
Author(s):  
C. Möstl ◽  
C. Miklenic ◽  
C. J. Farrugia ◽  
M. Temmer ◽  
A. Veronig ◽  
...  
Keyword(s):  
Interplanetary Space ◽  
Magnetic Cloud ◽  
Source Region ◽  
Flux Rope ◽  
Solar Wind Plasma ◽  
Heliospheric Current Sheet ◽  
Magnetic Clouds ◽  
Reconstruction Technique ◽  
Novel Approach ◽  
Poloidal Flux

Abstract. This paper compares properties of the source region with those inferred from satellite observations near Earth of the magnetic cloud which reached 1 AU on 20 November 2003. We use observations from space missions SOHO and TRACE together with ground-based data to study the magnetic structure of the active region NOAA 10501 containing a highly curved filament, and determine the reconnection rates and fluxes in an M4 flare on 18 November 2003 which is associated with a fast halo CME. This event has been linked before to the magnetic cloud on 20 November 2003. We model the near-Earth observations with the Grad-Shafranov reconstruction technique using a novel approach in which we optimize the results with two-spacecraft measurements of the solar wind plasma and magnetic field made by ACE and WIND. The two probes were separated by hundreds of Earth radii. They pass through the axis of the cloud which is inclined −50 degree to the ecliptic. The magnetic cloud orientation at 1 AU is consistent with an encounter with the heliospheric current sheet. We estimate that 50% of its poloidal flux has been lost through reconnection in interplanetary space. By comparing the flare ribbon flux with the original cloud fluxes we infer a flux rope formation during the eruption, though uncertainties are still significant. The multi-spacecraft Grad-Shafranov method opens new vistas in probing of the spatial structure of magnetic clouds in STEREO-WIND/ACE coordinated studies.

scholarly journals Reconstruction of magnetic clouds from in-situ spacecraft measurements and intercomparison with their solar sources

2013 ◽  
Vol 8 (S300) ◽  
pp. 269-272
Author(s):  
Qiang Hu ◽  
Jiong Qiu
Keyword(s):  
Magnetic Flux ◽  
Field Line ◽  
Source Region ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Reconstruction Technique ◽  
Magnetic Flux Rope ◽  
Solar Material ◽  
Physical Quantities

AbstractCoronal Mass Ejections (CMEs) are eruptive events that originate, propagate away from the Sun, and carry along solar material with embedded solar magnetic field. Some are accompanied by prominence eruptions. A subset of the interplanetary counterparts of CMEs (ICMEs), so-called Magnetic Clouds (MCs) can be characterized by magnetic flux-rope structures. We apply the Grad-Shafranov (GS) reconstruction technique to examine the configuration of MCs and to derive relevant physical quantities, such as magnetic flux content, relative magnetic helicity, and the field-line twist, etc. Both observational analyses of solar source region characteristics including flaring and associated magnetic reconnection process, and the corresponding MC structures were carried out. We summarize the main properties of selected events with and without associated prominence eruptions. In particular, we show the field-line twist distribution and the intercomparison of magnetic flux for these flux-rope structures.

scholarly journals Flux rope axis geometry of magnetic clouds deduced from in situ data

2013 ◽  
Vol 8 (S300) ◽  
pp. 265-268
Author(s):  
Miho Janvier ◽  
Pascal Démoulin ◽  
Sergio Dasso
Keyword(s):  
Interplanetary Medium ◽  
Magnetic Cloud ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Direct Integration ◽  
Axis Orientation ◽  
In Situ Data ◽  
Geometrical Features ◽  
Wide Range

AbstractMagnetic clouds (MCs) consist of flux ropes that are ejected from the low solar corona during eruptive flares. Following their ejection, they propagate in the interplanetary medium where they can be detected by in situ instruments and heliospheric imagers onboard spacecraft. Although in situ measurements give a wide range of data, these only depict the nature of the MC along the unidirectional trajectory crossing of a spacecraft. As such, direct 3D measurements of MC characteristics are impossible. From a statistical analysis of a wide range of MCs detected at 1 AU by the Wind spacecraft, we propose different methods to deduce the most probable magnetic cloud axis shape. These methods include the comparison of synthetic distributions with observed distributions of the axis orientation, as well as the direct integration of observed probability distribution to deduce the global MC axis shape. The overall shape given by those two methods is then compared with 2D heliospheric images of a propagating MC and we find similar geometrical features.

scholarly journals The link between CME-associated dimmings and interplanetary magnetic clouds

2008 ◽  
Vol 4 (S257) ◽  
pp. 265-270 ◽  
Author(s):  
Cristina H. Mandrini ◽  
María S. Nakwacki ◽  
Gemma Attrill ◽  
Lidia van Driel-Gesztelyi ◽  
Sergio Dasso ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Large Scale ◽  
Extreme Ultraviolet ◽  
Magnetic Cloud ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Magnetic Structures ◽  
Doppler Imager ◽  
Imaging Telescope

AbstractCoronal dimmings often develop in the vicinity of erupting magnetic configurations. It has been suggested that they mark the location of the footpoints of ejected flux ropes and, thus, their magnetic flux can be used as a proxy for the ejected flux. If so, this quantity can be compared to the flux in the associated interplanetary magnetic cloud (MC) to find clues about the origin of the ejected flux rope. In the context of this interpretation, we present several events for which we have done a comparative solar-interplanetary analysis. We combine SOHO/Extreme Ultraviolet Imaging Telescope (EIT) data and Michelson Doppler Imager (MDI) magnetic maps to identify and measure the flux in the dimmed regions. We model the associated MCs and compute their magnetic flux using in situ observations. We find that the magnetic fluxes in the dimmings and MCs are compatible in some events; though this is not the case for large-scale and intense eruptions that occur in regions that are not isolated from others. We conclude that, in these particular cases, a fraction of the dimmed regions can be formed by reconnection between the erupting field and the surrounding magnetic structures, via a stepping process that can also explain other CME associated events.

The magnetic flux rope structure of coronal mass ejections – 2021 Julius Bartels Medal Lecture at vEGU

2021 ◽  
Author(s):  
Volker Bothmer
Keyword(s):  
Magnetic Flux ◽  
White Light ◽  
Coronal Mass Ejections ◽  
Large Scale ◽  
Neutral Line ◽  
Source Region ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Small Scale ◽  
Magnetic Flux Rope

<div> <p><span>Magnetic clouds are transient solar wind flows in the interplanetary medium with smooth rotations of the magnetic field vector and low plasma beta values. The analysis of magnetic clouds identified in the data of the two Helios spacecraft between 0.3 and 1 AU showed that they can be interpreted to first order by force-free, large-scale, cylindrical magnetic flux tubes. A close correlation of their occurrences was found with disappearing filaments at the Sun. The magnetic clouds that originated from the northern solar hemisphere showed predominantly left-handed magnetic helicities and the ones from the southern hemisphere predominantly right-handed ones. They were often preceded by an interplanetary shock wave and some were found to be directly following a coronal mass ejection towards the Helios spacecraft as detected by the Solwind coronagraph on board the P78-1 satellite. With the SOHO mission unprecedented long-term observations of coronal mass ejections (CMEs) were taken with the LASCO coronagraphs, with a spatial and time resolution that allowed to investigate their internal white-light fine structure. With complementary photospheric and EUV observations from SOHO, CMEs were found to arise from pre-existing small scale loop systems, overlying regions of opposite magnetic polarities. From the characteristic pattern of their source regions in both solar hemispheres, a generic scheme was presented in which their projected white-light topology depends primarily on the orientation and position of the source region’s neutral line on the solar disk. Based on this interpretation the graduated cylindrical shell method was developed, which allowed to model the electron density distribution of CMEs as 3D flux ropes. This concept was validated through stereoscopic observations of CMEs taken by the coronagraphs of the SECCHI remote sensing suite on board the twin STEREO spacecraft. The observations further revealed that the dynamic near-Sun evolution of CMEs often leads to distortions of their flux rope structure. However, the magnetic flux rope concept of CMEs is today one of the fundamental methods in space weather forecasts. With the Parker Solar Probe we currently observe for the first time CMEs in-situ and remotely at their birthplaces in the solar corona and can further unravel their origin and evolution from the corona into the heliosphere. This lecture provides a state-of-the-art overview on the magnetic structure of CMEs and includes latest observations from the Parker Solar Probe mission.</span></p> </div>

scholarly journals New Force-Free Models of Magnetic Clouds

2005 ◽  
Vol 13 ◽  
pp. 133-133
Author(s):  
M. Vandas ◽  
E. P. Romashets ◽  
S. Watari
Keyword(s):  
Magnetic Field ◽  
Magnetic Cloud ◽  
Free Field ◽  
Flux Rope ◽  
Field Vector ◽  
Magnetic Clouds ◽  
Field Magnitude ◽  
Flux Ropes ◽  
Magnetic Field Magnitude ◽  
The Magnetic Field

AbstractMagnetic clouds are thought to be large flux ropes propagating through the heliosphere. Their twisted magnetic fields are mostly modeled by a constant-alpha force-free field in a circular cylindrical flux rope (the Lundquist solution). However, the interplanetary flux ropes are three dimensional objects. In reality they possibly have a curved shape and an oblate cross section. Recently we have found two force-free models of flux ropes which takes into account the mentioned features. These are (i) a constant-alpha force-free configuration in an elliptic flux rope (Vandas & Romashets 2003, A&A, 398, 801), and (ii) a non-constant-alpha force-free field in a toroid with arbitrary aspect ratio (Romashets & Vandas 2003, AIP Conf Ser. 679, 180). Two magnetic cloud observations were analyzed. The magnetic cloud of October 18-19, 1995 has been fitted by Lepping et al. (1997, JGR, 102, 14049) with use of the Lundquist solution. The cloud has a very flat magnetic field magnitude profile. We fitted it by the elliptic solution (i). The magnetic cloud of November 17-18, 1975 has been fitted by Marubashi (1997) with use of a toroidally adjusted Lundquist solution. The cloud has a large magnetic field vector rotation and a large magnetic field magnitude increase over the background level. We fitted it by the toroidal solution (ii). The both fits match the rotation of the magnetic field vector in a comparable quality to the former fits, but the description of the magnetic field magnitude profiles is remarkable better. It is possible to incorporate temporal effects (expansion) of magnetic clouds into the new solutions through a time-dependent alpha parameter as in Shimazu & Vandas (2002, EP&S, 54, 783).

scholarly journals Magnetic Cloud as a Dual-Polarity Flux Rope

2001 ◽  
Vol 203 ◽  
pp. 541-543
Author(s):  
M. Vandas ◽  
A. Geranios
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Strong Magnetic Field ◽  
Magnetic Cloud ◽  
Flux Rope ◽  
Solar Wind Plasma ◽  
Magnetic Polarity ◽  
Annular Region ◽  
The Core ◽  
Dual Polarity

The magnetic cloud of November 17-18, 1975 is analyzed and it is shown that measurements of magnetic field and solar wind plasma are consistent with the interpretation that this magnetic cloud is a dual-polarity flux rope which consists of a core and an annular region. The core has a strong magnetic field; the annular region has a higher plasma density and opposite magnetic polarity.

scholarly journals On the Radial and Longitudinal Variation of a Magnetic Cloud: ACE, Wind, ARTEMIS and Juno Observations

Solar Physics ◽  
2020 ◽  
Vol 295 (11) ◽  
Author(s):  
Emma E. Davies ◽  
Robert J. Forsyth ◽  
Simon W. Good ◽  
Emilia K. J. Kilpua
Keyword(s):  
Axial Magnetic Field ◽  
Magnetic Cloud ◽  
Flux Rope ◽  
Time History ◽  
Minimum Variance ◽  
Magnetic Clouds ◽  
Analysis Method ◽  
History Of

AbstractWe present observations of the same magnetic cloud made near Earth by the Advance Composition Explorer (ACE), Wind, and the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) mission comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and THEMIS C spacecraft, and later by Juno at a distance of 1.2 AU. The spacecraft were close to radial alignment throughout the event, with a longitudinal separation of $3.6^{\circ}$ 3.6 ∘ between Juno and the spacecraft near Earth. The magnetic cloud likely originated from a filament eruption on 22 October 2011 at 00:05 UT, and caused a strong geomagnetic storm at Earth commencing on 24 October. Observations of the magnetic cloud at each spacecraft have been analysed using minimum variance analysis and two flux rope fitting models, Lundquist and Gold–Hoyle, to give the orientation of the flux rope axis. We explore the effect different trailing edge boundaries have on the results of each analysis method, and find a clear difference between the orientations of the flux rope axis at the near-Earth spacecraft and Juno, independent of the analysis method. The axial magnetic field strength and the radial width of the flux rope are calculated using both observations and fitting parameters and their relationship with heliocentric distance is investigated. Differences in results between the near-Earth spacecraft and Juno are attributed not only to the radial separation, but to the small longitudinal separation which resulted in a surprisingly large difference in the in situ observations between the spacecraft. This case study demonstrates the utility of Juno cruise data as a new opportunity to study magnetic clouds beyond 1 AU, and the need for caution in future radial alignment studies.

Constraining the CME parameters of the spheromak flux rope implemented in EUHFORIA

2021 ◽  
Author(s):  
Eleanna Asvestari ◽  
Jens Pomoell ◽  
Emilia Kilpua ◽  
Simon Good ◽  
Theodosios Chatzistergos ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Space Weather ◽  
Weather Forecasting ◽  
Interplanetary Space ◽  
Source Region ◽  
Flux Rope ◽  
Field Configuration ◽  
Arrival Times ◽  
Sheath Region ◽  
Region Length

<p>Coronal mass ejections (CMEs) are primary drivers of space weather phenomena. Modelling the evolution of the internal magnetic field configuration of CMEs as they propagate through the interplanetary space is an essential part of space weather forecasting. EUHFORIA (EUropean Heliospheric FORecasting Information Asset) is a data-driven, physics-based model, able to trace the evolution of CMEs and CME-driven shocks through realistic background solar wind conditions. It employs a spheromak-type magnetic flux rope that is initially force-free, providing it with the advantage of modelling CME as magnetised structures. For this work we assessed the spheromak CME model employed in EUHFORIA with a test CME case study. The selected CME eruption occurred on the 6th of January 2013 and was encountered by two spacecraft, Venus Express and STEREO--A, which were radially aligned at the time of the CME passage. Our focus was to constrain the input parameters, with particular interest in: (1) translating the angular widths of the graduated cylindrical shell (GCS) fitting to the spheromak radius, and (2) matching the observed magnetic field topology at the source region. We ran EUHFORIA with three different spheromak radii. The model predicts arrival times from half to a full day ahead of the one observed <em>in situ</em>. We conclude that the choice of spheromak radius affected the modelled magnetic field profiles, their amplitude, arrival times, and sheath region length.</p>

scholarly journals Evolution of the 5 January 2005 CMEs associated with eruptive filaments in inner heliosphere

2013 ◽  
Vol 8 (S300) ◽  
pp. 491-492 ◽  
Author(s):  
Rahul Sharma ◽  
Nandita Srivastava ◽  
Bernard V. Jackson ◽  
D. Chakrabarty ◽  
Nolan Luckett ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Flux Rope ◽  
Recovery Phase ◽  
Magnetic Clouds ◽  
Reconstruction Technique ◽  
Solar Mass ◽  
Magnetic Structures ◽  
Solar Mass Ejection Imager ◽  
Mass Ejection ◽  
Filament Plasma

AbstractOn 5 January 2005, SoHO/LASCO observed two CMEs associated with eruptive filaments with different initial velocities and acceleration. The second CME accelerates much faster than the previous and the resulting interaction has been revealed in in-situ spacecraft measurements by the presence of magnetic holes at the border of the two distinct magnetic clouds. At their interface region, these magnetic clouds have embedded filament plasma that shows complex magnetic structures with a distinct magnetic flux rope configuration; these have been modeled by the Grad - Shafranov reconstruction technique. The geomagnetic consequences of these structures have been associated with substorms in recovery phase of a storm and detailed analysis is presented in Sharma et al. (2013). In the present paper, we highlight the comparison of shape and extent of two filament plasma remnants in magnetic clouds as revealed by three - dimensional (3D) reconstruction and analysis from the Solar Mass Ejection Imager (SMEI) data. The results provide an overview of the two eruptive filaments on 5 January 2005 and their interplanetary propagation.

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