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Forward Modeling of Coronal Mass Ejection Flux Ropes in the Inner Heliosphere with 3DCORE  

Christian Möstl   Submitted: 2018-03-08 02:09

Forecasting the geomagnetic effects of solar storms, known as coronal mass ejections (CMEs), is currently severely limited by our inability to predict the magnetic field configuration in the CME magnetic core and by observational effects of a single spacecraft trajectory through its 3D structure. CME magnetic flux ropes can lead to continuous forcing of the energy input to the Earth's magnetosphere by strong and steady southward-pointing magnetic fields. Here, we demonstrate in a proof-of-concept way a new approach to predict the southward field Bz in a CME flux rope. It combines a novel semi-empirical model of CME flux rope magnetic fields (3-Dimensional Coronal ROpe Ejection or 3DCORE) with solar observations and in situ magnetic field data from along the Sun-Earth line. These are provided here by the MESSENGER spacecraft for a CME event on 2013 July 9-13. 3DCORE is the first such model that contains the interplanetary propagation and evolution of a 3D flux rope magnetic field, the observation by a synthetic spacecraft and the prediction of an index of geomagnetic activity. A counterclockwise rotation of the left-handed erupting CME flux rope in the corona of 30 degree and a deflection angle of 20 degree is evident from comparison of solar and coronal observations. The calculated Dst matches reasonably the observed Dst minimum and its time evolution, but the results are highly sensitive to the CME axis orientation. We discuss assumptions and limitations of the method prototype and its potential for real time space weather forecasting and heliospheric data interpretation.

Authors: C. Möstl, T. Amerstorfer, E. Palmerio, A. Isavnin, C. J. Farrugia, C. Lowder, R. M. Winslow, J. M. Donnerer, E. K. J. Kilpua, P. D. Boakes
Projects: SDO-AIA,SDO-HMI,SoHO-LASCO,STEREO,Wind

Publication Status: published in AGU Space Weather, doi: 10.1002/2017SW001735
Last Modified: 2018-03-08 09:44
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Strong coronal channelling and interplanetary evolution of a solar storm up to Earth and Mars  

Christian Möstl   Submitted: 2015-06-11 01:33

The severe geomagnetic effects of solar storms or coronal mass ejections (CMEs) are to a large degree determined by their propagation direction with respect to Earth. There is a lack of understanding of the processes that determine their non-radial propagation. Here we present a synthesis of data from seven different space missions of a fast CME, which originated in an active region near the disk centre and, hence, a significant geomagnetic impact was forecasted. However, the CME is demonstrated to be channelled during eruption into a direction + 37 ±10 degree (longitude) away from its source region, leading only to minimal geomagnetic effects. In situ observations near Earth and Mars confirm the channelled CME motion, and are consistent with an ellipse shape of the CME-driven shock provided by the new Ellipse Evolution model, presented here. The results enhance our understanding of CME propagation and shape, which can help to improve space weather forecasts.

Authors: C. Möstl, T. Rollett, R. A. Frahm, Y. D. Liu, D. M. Long, R. C. Colaninno, M. A. Reiss, M. Temmer, C. J. Farrugia, A. Posner, M. Dumbovic, M. Janvier, P. Demoulin, P. Boakes, A. Devos, E. Kraaikamp, M. L. Mays, B. Vrsnak
Projects: SDO-AIA,SDO-HMI,SoHO-LASCO,STEREO,Wind

Publication Status: published in Nature Communications as open access: http://www.nature.com/ncomms/2015/150526/ncomms8135/full/ncomms8135.html
Last Modified: 2015-06-11 14:19
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Connecting speeds, directions and arrival times of 22 coronal mass ejections from the Sun to 1 AU  

Christian Möstl   Submitted: 2014-04-15 01:51

Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather, and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to 2700 km s-1). We track the CMEs to 34.9?7.1 degrees elongation from the Sun with J-maps constructed using the SATPLOT tool, resulting in prediction lead times of -26.4?15.3 hours. The geometrical models we use assume different CME front shapes (Fixed-Phi, Harmonic Mean, Self-Similar Expansion), and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is 8.1?6.3 hours (rms value of 10.9h). Speeds are consistent to within 284?288 km s-1. Empirical corrections to the predictions enhance their performance for the arrival times to 6.1?5.0 hours (rms value of 7.9h), and for the speeds to 53?50 km s-1. These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line.

Authors: C. Möstl, K. Amla, J. R. Hall, P. C. Liewer, E. M. De Jong, R. C. Colaninno, A. M. Veronig, T. Rollett, M. Temmer, V. Peinhart, J. A. Davies, N. Lugaz, Y. D. Liu, C.J. Farrugia, J. G. Luhmann, B. Vr?nak, R. A. Harrison, A. B. Galvin
Projects: STEREO,Wind

Publication Status: ApJ (in press)
Last Modified: 2014-04-16 13:14
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Multi-point shock and flux rope analysis of multiple interplanetary coronal mass ejections around 2010 August 1 in the inner heliosphere  

Christian Möstl   Submitted: 2012-09-14 05:31

We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions (Solar Dynamics Observatory/ Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory) monitored several CMEs originating within tens of degrees from solar disk center. We compare their imprints on four widely separated locations, spanning 120 degree in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE and ARTEMIS near Earth, and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index (~ -100 nT), caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs.

Authors: C. Möstl, C.J. Farrugia, E.K.J. Kilpua, L.K. Jian, Y. Liu, J. Eastwood, R. A. Harrison, D.F. Webb, M. Temmer, D. Odstrcil, J.A. Davies, T. Rollett, J.G. Luhmann, N. Nitta, T. Mulligan, E. A. Jensen, R. Forsyth, B. Lavraud, C. A. De Koning, A. M. Veronig, A. B. Galvin, T. L. Zhang, B.J. Anderson
Projects: ACE,STEREO,Wind

Publication Status: ApJ (in press)
Last Modified: 2012-09-14 10:07
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Speeds and arrival times of solar transients approximated by self-similar expanding circular fronts  

Christian Möstl   Submitted: 2012-02-14 13:18

The NASA STEREO mission opened up the possibility to forecast thearrivaltimes, speeds and directions of solar transients from outside theSun-Earth line.In particular, we are interested in predicting potentiallygeo-effective InterplanetaryCoronal Mass Ejections (ICMEs) from observations of density structuresatlarge observation angles from the Sun (with the STEREO HeliosphericImagerinstrument). We contribute to this endeavor by deriving analyticalformulasconcerning a geometric correction for the ICME speed and arrival timefor thetechnique introduced by Davies et al. (2012, submitted to ApJ) calledSelf-Similar Expansion Fitting (SSEF). This model assumes that a circlepropagatesoutward, along a plane specified by a position angle (e.g. theecliptic), with constantangular half width (λ). This is an extension to earlier, more simplemodels:Fixed-φ Fitting (&lambda=0°) and Harmonic Mean Fitting(λ = 90°)This approachhas the advantage that it is possible to assess clearly, in contrastto previousmodels, if a particular location in the heliosphere, such as a planetor spacecraft,might be expected to be hit by the ICME front. Our correction formulasareespecially significant for glancing hits, where small differences inthe directiongreatly influence the expected speeds (up to 100-200 kms-1) and arrival times(up to two days later than the apex). For very wide ICMEs (2&lambda >120°), thegeometric correction becomes very similar to the one derived byMoestl et al.(2011, ApJ) for the Harmonic Mean model. These analytic expressionscan alsobe used for empirical or analytical models to predict the 1 AU arrivaltime of anICME by correcting for effects of hits by the flank rather than theapex, if thewidth and direction of the ICME in a plane are known and a circulargeometryof the ICME front is assumed.

Authors: Christian Möstl and Jackie A. Davies
Projects: STEREO

Publication Status: accepted for publication in Solar Physics
Last Modified: 2012-02-17 08:43
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Arrival time calculation for interplanetary coronal mass ejections with circular fronts and application to STEREO observations of the 2009 February 13 eruption  

Christian Möstl   Submitted: 2011-08-02 02:34

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: C. Möstl, T. Rollett, N. Lugaz, C. J. Farrugia, J. A. Davies, M. Temmer, A. M. Veronig, R. Harrison, S. Crothers, J. G. Luhmann, A. B. Galvin, T. L. Zhang, W. Baumjohann, H. K. Biernat
Projects: STEREO

Publication Status: ApJ, accepted
Last Modified: 2011-08-02 14:59
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STEREO and Wind observations of a fast ICME flank triggering a prolonged geomagnetic storm on 5-7 April 2010  

Christian Möstl   Submitted: 2010-10-21 04:54

On 5 April 2010 an interplanetary (IP) shock was detected by the Wind spacecraft ahead of Earth, followed by a fast (average speed 650 km s-1) IP coronal mass ejection (ICME). During the subsequent moderate geomagnetic storm (minimum Dst = -72 nT, maximum Kp = 8-), communication with the Galaxy 15 satellite was lost. We link images from STEREO/ SECCHI to the near?Earth in situ observations and show that the ICME did not decelerate much between Sun and Earth. The ICME flank was responsible for a long storm growth phase. This type of glancing collision was for the first time directly observed with the STEREO Heliospheric Imagers. The magnetic cloud (MC) inside the ICME cannot be modeled with approaches assuming an invariant direction. These observations confirm the hypotheses that parts of ICMEs classified as (1) long?duration MCs or (2) magnetic? cloud?like (MCL) structures can be a consequence of a spacecraft trajectory through the ICME flank.

Authors: Möstl, C., M. Temmer, T. Rollett, C.J. Farrugia, Y. Liu, A. Veronig, M. Leitner, A.B. Galvin, H.K. Biernat
Projects: STEREO

Publication Status: Geophysical Research Letters (in press)
Last Modified: 2010-10-21 05:39
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Linking remote imagery of a coronal mass ejection to its in situ signatures at 1 AU  

Christian Möstl   Submitted: 2009-10-07 04:28

In a case study (June 6-7, 2008) we report on how the internal structure of a coronal mass ejection (CME) at 1 AU can be anticipated from remote observations of white-light images of the heliosphere. Favorable circumstances are the absence of fast equatorial solar wind streams and a low CME velocity which allow us to relate the imaging and in-situ data in a straightforward way. The STEREO-B spacecraft encountered typical signatures of a magnetic flux rope inside an interplanetary CME (ICME) whose axis was inclined at 45 degree to the solar equatorial plane. Various CME direction-finding techniques yield consistent results to within 15 degree. Further, remote images from STEREO-A show that (1) the CME is unambiguously connected to the ICME and can be tracked all the way to 1 AU, (2) the particular arc-like morphology of the CME points to an inclined axis, and (3) the three-part structure of the CME may be plausibly related to the in situ data. This is a first step in predicting both the direction of travel and the internal structure of CMEs from complete remote observations between the Sun and 1 AU, which is one of the main requirements for forecasting the geo-effectiveness of CMEs.

Authors: Christian Möstl, Charles J. Farrugia, Manuela Temmer, Christiane Miklenic, Astrid M. Veronig, Antoinette B. Galvin, Martin Leitner, Helfried K. Biernat
Projects: STEREO

Publication Status: ApJL, accepted
Last Modified: 2009-10-08 07:41
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Optimized Grad-Shafranov reconstruction of a magnetic cloud using STEREO-WIND observations  

Christian Möstl   Submitted: 2009-04-06 07:18

We present results on the geometry of a magnetic cloud on 23 May 2007 from a comprehensive analysis of WIND and STEREO observations. We first apply a Grad-Shafranov reconstruction to the STEREO-A plasma and magnetic field data, delivered by the PLASTIC and IMPACT instruments. We then optimize the resulting field map with the aid of observations by WIND, which were made at the very outer boundary of the cloud, at a spacecraft angular separation of 6 degree. For the correct choice of reconstruction parameters such as axis orientation, interval and grid size, we find both a very good match between the predicted magnetic field at the position of WIND and the actual observations as well as consistent timing. We argue that the reconstruction captures almost the full extent of the cloud's cross-section. The resulting shape transverse to the invariant axis consists of distorted ellipses and is slightly flattened in the direction of motion. The MC axis is inclined at -58 degree to the ecliptic with an axial field strength of 12 nT, and we derive integrated axial fluxes and currents with increased precision, which we contrast with the results from linear force-free fitting. The helical geometry of the MC with almost constant twist (~1.5 turns per AU) is not consistent with the linear force-free Lundquist model. We also find that the cloud is non-force-free (j_perpendicular/j_parallel > 0.3) in about a quarter of the cloud's cross sectional area, particularly in the back part which is interacting with the trailing high speed stream. Based on the optimized reconstruction we put forward preliminary guidelines for the improved use of single-spacecraft Grad-Shafranov reconstruction. The results also give us the opportunity to compare the CME direction inferred from STEREO/SECCHI observations by Mierla et al., (Solar Phys. 252, 385, 2008) with the three-dimensional configuration of the magnetic cloud at 1 AU. This yields an almost radial CME propagation from the Sun to the Earth.

Authors: Möstl, C., C.J. Farrugia, H.K. Biernat, M. Leitner, E.K.J. Kilpua, A.B. Galvin, J.G. Luhmann
Projects: STEREO

Publication Status: accepted
Last Modified: 2009-04-08 09:23
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Multi-spacecraft recovery of a magnetic cloud and its origin from magnetic reconnection on the Sun  

Christian Möstl   Submitted: 2009-01-12 07:36

Multi-point spacecraft observations of a magnetic cloud on May 22, 2007 has given us the opportunity to apply a multi- spacecraft technique to infer the structure of this large-scale magnetic flux rope in the solar wind. Combining WIND and STEREO-B magnetic field and plasma measurements we construct a combined magnetic field map by integrating the Grad-Shafranov equation, this being one of the very first applications of this technique in the interplanetary context. From this we obtain robust results on the shape of the cross-section, the orientation and magnetic fluxes of the cloud. The only slightly flattened shape is discussed with respect to its heliospheric environment and theoretical expectations. We also relate these results to observations of the solar source region and its associated two-ribbon flare on May 19, 2007, using Hα images from the Kanzelhoehe observatory, SOHO/MDI magnetograms and SECCHI/EUVI 171 Å images. We find a close correspondence between the magnetic flux reconnected in the flare and the poloidal flux of the magnetic cloud. The axial flux of the cloud agrees with the prediction of a recent 3D finite sheared arcade model to within a factor of 2, which is evidence for formation of at least half of the magnetic flux of the ejected flux rope during the eruption. We outline the relevance of this result to models of coronal mass ejection initiation, and find that to explain the solar and interplanetary observations elements from sheared-arcade as well as erupting-flux-rope models are needed.

Authors: C. Möstl, C.J. Farrugia, C. Miklenic, M. Temmer, A.B. Galvin, J.G. Luhmann, E.K.J. Kilpua, M.Leitner, T. Nieves-Chinchilla, A. Veronig, H.K. Biernat
Projects: SoHO-MDI,STEREO

Publication Status: JGR (space physics), accepted
Last Modified: 2009-01-13 01:01
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Subject will be restored when possible  

Christian Möstl   Submitted: 2008-01-21 08:16

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.

Authors: Möstl, C., Miklenic, C., Farrugia, C.J., Temmer, M., Veronig, A., Galvin, A.B., Vrsnak, B., Biernat, H. K.
Projects: None

Publication Status: Annales Geophysicae (accepted)
Last Modified: 2008-01-22 08:30
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Subject will be restored when possible  

Christian Möstl   Submitted: 2008-01-21 08:15

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.

Authors: Möstl, C., Miklenic, C., Farrugia, C.J., Temmer, M., Veronig, A., Galvin, A.B., Vrsnak, B., Biernat, H. K.
Projects: None

Publication Status: Annales Geophysicae (accepted)
Last Modified: 2008-01-21 08:15
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Abstracts by Author
Forward Modeling of Coronal Mass Ejection Flux Ropes in the Inner Heliosphere with 3DCORE
Strong coronal channelling and interplanetary evolution of a solar storm up to Earth and Mars
Connecting speeds, directions and arrival times of 22 coronal mass ejections from the Sun to 1 AU
Multi-point shock and flux rope analysis of multiple interplanetary coronal mass ejections around 2010 August 1 in the inner heliosphere
Speeds and arrival times of solar transients approximated by self-similar expanding circular fronts
Arrival time calculation for interplanetary coronal mass ejections with circular fronts and application to STEREO observations of the 2009 February 13 eruption
STEREO and Wind observations of a fast ICME flank triggering a prolonged geomagnetic storm on 5-7 April 2010
Linking remote imagery of a coronal mass ejection to its in situ signatures at 1 AU
Optimized Grad-Shafranov reconstruction of a magnetic cloud using STEREO-WIND observations
Multi-spacecraft recovery of a magnetic cloud and its origin from magnetic reconnection on the Sun
Subject will be restored when possible
Subject will be restored when possible

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