Interplanetary Coronal Mass Ejections Observed in the Heliosphere: 1. Review of Theory

Howard, T. A.; Tappin, S. J.

doi:10.1007/s11214-009-9542-5

Cited by 134 publications

(161 citation statements)

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“…Assuming that the CME observed in white-light is due to Thomson scattered photospheric light from the electrons in the CME (Minnaert, 1930;Billings, 1966;Howard and Tappin, 2009), the recorded scattered intensity can then be converted into the number of electrons, and hence the mass of a CME can be estimated, assuming a completely ionized corona with a composition of 90% hydrogen and 10% helium. In earlier studies (Munro et al, 1979;Poland et al, 1981;Vourlidas et al, 2000), the mass of a CME was calculated assuming the CME location in the observer's plane of sky.…”

Section: Momentum Energy Exchange and Nature Of The Collisionmentioning

confidence: 99%

Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13 – 14 June 2012

2018

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We report on the kinematics of two interacting CMEs observed on 13 and 14 June 2012. Both CMEs originated from the same active region NOAA 11504. After their launches which were separated by several hours, they were observed to interact at a distance of 100 R from the Sun. The interaction led to a moderate geomagnetic storm at the Earth with D st index of approximately, -86 nT. The kinematics of the two CMEs is estimated using data from the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) onboard the Solar Terrestrial Relations Observatory (STEREO). Assuming a head-on collision scenario, we find that the collision is inelastic in nature. Further, the signatures of their interaction are examined using the in situ observations obtained by Wind and the Advance Composition Explorer (ACE) spacecraft. It is also found that this interaction event led to the strongest sudden storm commencement (SSC) (≈ 150 nT) of the present Solar Cycle 24. The SSC was of long duration, approximately 20 hours. The role of interacting CMEs in enhancing the geoeffectiveness is examined.

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Section: Momentum Energy Exchange and Nature Of The Collisionmentioning

confidence: 99%

Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13 – 14 June 2012

2018

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“…This definition is visualized in Figure 1. It is further assumed that the observer always measures the resulting elongation angle by looking along the tangent to this circle (see Figure 1 and Lugaz et al 2009;Howard & Tappin 2009a). The radial distance of the circle's apex R HM , the point with the greatest distance from the Sun, is given by Lugaz et al (2009):…”

Section: Fixed-φ and Harmonic Meanmentioning

confidence: 99%

“…The intensities in the images are related to Thomson scattering of white-light solar radiation off solar wind electrons, and the incident intensity for a given observer maximizes along the line of sight at the Thomson surface (Vourlidas & Howard 2006;Howard & Tappin 2009a; see also Figure 6). The reader is referred to the HI1A/HI2A movie in the online journal.…”

Section: Stereo-a Heliospheric Imaging Observationsmentioning

confidence: 99%

“…There exist two practical realizations of this concept: the original technique (Rouillard et al 2008), which assumes a point-like or negligibly narrow shape of the CME front (also called the fixed-Φ approximation; we call this fixed-Φ fitting or FPF), and the method by Lugaz (2010), which assumes a circular CME front, attached to the Sun at all times at one end (harmonic mean fitting or HMF). Note that there also exist more complex approaches to the same problem, such as the Tappin-Howard (T-H) model (Howard & Tappin 2009aTappin & Howard 2009), in which a large set of pre-existing solutions is fitted to the observations, which is also useful for real-time application, and the white-light rendering method by Wood & Howard (2009). In this study we use the FPF and HMF methods, and we present the formulae for converting elongation to distance with FP/HM and the inverted method useful for predicting ICME parameters with FPF/HMF.…”

Section: Introductionmentioning

confidence: 99%

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ARRIVAL TIME CALCULATION FOR INTERPLANETARY CORONAL MASS EJECTIONS WITH CIRCULAR FRONTS AND APPLICATION TOSTEREOOBSERVATIONS OF THE 2009 FEBRUARY 13 ERUPTION

Möstl

Rollett

Lugaz

et al. 2011

ApJ

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One of the goals of the NASA Solar TErestrial RElations Observatory (STEREO) mission is to study the feasibility of forecasting the direction, arrival time, and internal structure of solar coronal mass ejections (CMEs) from a vantage point outside the Sun-Earth line. Through a case study, we discuss the arrival time calculation of interplanetary CMEs (ICMEs) in the ecliptic plane using data from STEREO/SECCHI at large elongations from the Sun in combination with different geometric assumptions about the ICME front shape [fixed-Φ (FP): a point and harmonic mean (HM): a circle]. These forecasting techniques use single-spacecraft imaging data and are based on the assumption of constant velocity and direction. We show that for the slow (350 km s −1 ) ICME on 2009 February 13-18, observed at quadrature by the two STEREO spacecraft, the results for the arrival time given by the HM approximation are more accurate by 12 hr than those for FP in comparison to in situ observations of solar wind plasma and magnetic field parameters by STEREO/IMPACT/PLASTIC, and by 6 hr for the arrival time at Venus Express (MAG). We propose that the improvement is directly related to the ICME front shape being more accurately described by HM for an ICME with a low inclination of its symmetry axis to the ecliptic. In this case, the ICME has to be tracked to >30 • elongation to obtain arrival time errors <± 5 hr. A newly derived formula for calculating arrival times with the HM method is also useful for a triangulation technique assuming the same geometry.

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“…Various techniques have been developed that enable the spatial locations and propagation directions of CMEs to be inferred, based on fitting their moving radiance patterns (e.g., Sheeley et al 2008;Rouillard et al 2008;Thernisien et al 2009;Liu et al 2010;Lugaz et al 2010;Möstl et al 2011;Davies et al 2012). However, the determination of interplanetary CME kinematics, and propagation direction in particular, is somewhat ambiguous (Howard & Tappin 2009;Davis et al 2010;Davies et al 2012;Howard & DeForest 2012;Xiong et al 2013;Lugaz & Kintner 2013). …”

Section: Heliospheric White Light Observationsmentioning

confidence: 99%

Using Coordinated Observations in Polarized White Light and Faraday Rotation to Probe the Spatial Position and Magnetic Field of an Interplanetary Sheath

Xiong

Davies

Feng

et al. 2013

ApJ

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Coronal mass ejections (CMEs) can be continuously tracked through a large portion of the inner heliosphere by direct imaging in visible and radio wavebands. White light (WL) signatures of solar wind transients, such as CMEs, result from Thomson scattering of sunlight by free electrons and therefore depend on both viewing geometry and electron density. The Faraday rotation (FR) of radio waves from extragalactic pulsars and quasars, which arises due to the presence of such solar wind features, depends on the line-of-sight magnetic field component B and the electron density. To understand coordinated WL and FR observations of CMEs, we perform forward magnetohydrodynamic modeling of an Earth-directed shock and synthesize the signatures that would be remotely sensed at a number of widely distributed vantage points in the inner heliosphere. Removal of the background solar wind contribution reveals the shock-associated enhancements in WL and FR. While the efficiency of Thomson scattering depends on scattering angle, WL radiance I decreases with heliocentric distance r roughly according to the expression I ∝ r −3 . The sheath region downstream of the Earth-directed shock is well viewed from the L4 and L5 Lagrangian points, demonstrating the benefits of these points in terms of space weather forecasting. The spatial position of the main scattering site r sheath and the mass of plasma at that position M sheath can be inferred from the polarization of the shock-associated enhancement in WL radiance. From the FR measurements, the local B sheath at r sheath can then be estimated. Simultaneous observations in polarized WL and FR can not only be used to detect CMEs, but also to diagnose their plasma and magnetic field properties.

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Interplanetary Coronal Mass Ejections Observed in the Heliosphere: 1. Review of Theory

Cited by 134 publications

References 38 publications

Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13 – 14 June 2012

Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13 – 14 June 2012

ARRIVAL TIME CALCULATION FOR INTERPLANETARY CORONAL MASS EJECTIONS WITH CIRCULAR FRONTS AND APPLICATION TOSTEREOOBSERVATIONS OF THE 2009 FEBRUARY 13 ERUPTION

Using Coordinated Observations in Polarized White Light and Faraday Rotation to Probe the Spatial Position and Magnetic Field of an Interplanetary Sheath

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