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Gloeckler, G.; Cain, J.; Ipavich, F. M.; Tums, E. O.; Bedini, Peter D.; Fisk, L. A.; Zurbuchen, T. H.; Bochsler, P.; Fischer, J.; Wimmer‐Schweingruber, R. F.; Geiss, J.; Kallenbach, R.

doi:10.1023/a:1005036131689

Cited by 301 publications

(152 citation statements)

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“…For a spacecraft at ∼1 au and a solar wind speed of 400 km s −1 , ∼315°corresponds to outwardly directed Parker spiral magnetic field, and ∼135°to an inward magnetic field. These directions are indicated by the dashed horizontal lines labeled OUT and IN, (e) the solar wind speed, (f) solar wind proton density, and (g) solar wind proton temperature as measured by the PLASTIC instruments on board the STEREO spacecraft (Galvin et al 2008) and the SWICS instrument on board ACE (Gloeckler et al 1998).…”

Section: Magnetic Field Configuration and Connectivity Prior To The Smentioning

confidence: 99%

The Solar Energetic Particle Event of 2010 August 14: Connectivity with the Solar Source Inferred from Multiple Spacecraft Observations and Modeling

Lario

Kwon

Richardson

et al. 2017

ApJ

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We analyze one of the first solar energetic particle (SEP) events of solar cycle 24 observed at widely separated spacecraft in order to assess the reliability of models currently used to determine the connectivity between the sources of SEPs at the Sun and spacecraft in the inner heliosphere. This SEP event was observed on 2010 August 14 by near-Earth spacecraft, STEREO-A (∼80°west of Earth) and STEREO-B (∼72°east of Earth). In contrast to near-Earth spacecraft, the footpoints of the nominal magnetic field lines connecting STEREO-A and STEREO-B with the Sun were separated from the region where the parent fast halo coronal mass ejection (CME) originated by ∼88°and ∼47°in longitude, respectively. We discuss the properties of the phenomena associated with this solar eruption. Extreme ultraviolet and white-light images are used to specify the extent of the associated CME-driven coronal shock. We then assess whether the SEPs observed at the three heliospheric locations were accelerated by this shock or whether transport mechanisms in the corona and/or interplanetary space provide an alternative explanation for the arrival of particles at the poorly connected spacecraft. A possible scenario consistent with the observations indicates that the observation of SEPs at STEREO-B and near Earth resulted from particle injection by the CME shock onto the field lines connecting to these spacecraft, whereas SEPs reached STEREO-A mostly via cross-field diffusive transport processes. The successes, limitations, and uncertainties of the methods used to resolve the connection between the acceleration sites of SEPs and the spacecraft are evaluated.

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Section: Magnetic Field Configuration and Connectivity Prior To The Smentioning

confidence: 99%

The Solar Energetic Particle Event of 2010 August 14: Connectivity with the Solar Source Inferred from Multiple Spacecraft Observations and Modeling

Lario

Kwon

Richardson

et al. 2017

ApJ

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“…At that time, both satellites were located upstream of the Earth at the L1 point. We obtained the magnetic field data from the Wind/MFI (Lepping et al 1995) and ACE/MAG (Smith et al 1998), the plasma data from the Wind/SWE (Ogilvie et al 1995) and ACE/SWEPAM (McComas et al 1998), and ionic composition from ACE/SWICS (Gloeckler et al 1998). The time resolution ranged from 1 minute to 2 hours for different data sets.…”

Section: Interplanetary Observationsmentioning

confidence: 99%

Redefining the Boundaries of Interplanetary Coronal Mass Ejections From Observations at the Ecliptic Plane

Cid

Palacios

Sáiz

et al. 2016

ApJ

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On 2015 January 6-7, an interplanetary coronal mass ejection (ICME) was observed at L1. This event, which can be associated with a weak and slow coronal mass ejection, allows us to discuss on the differences between the boundaries of the magnetic cloud and the compositional boundaries. A fast stream from a solar coronal hole surrounding this ICME offers a unique opportunity to check the boundaries' process definition and to explain differences between them. Using Wind and ACE data, we perform a complementary analysis involving compositional, magnetic, and kinematic observations providing relevant information regarding the evolution of the ICME as travelling away from the Sun. We propose erosion, at least at the front boundary of the ICME, as the main reason for the difference between the boundaries, and compositional signatures as the most precise diagnostic tool for the boundaries of ICMEs.

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“…Figure 1 plots O +7 /O +6 and the SW Fe/O abundance ratios versus SW helium speed in the non-interplanetary-CME (non-ICME) SW during years [2004][2005][2006], using Level-2, 2 hr averages measured by the Solar Wind Ion Composition Spectrometer (SWICS; Gloeckler et al 1998) on the Advanced Composition Explorer (ACE). Also shown are histograms for these quantities in typical slow and fast SW speed regimes.…”

Section: Introductionmentioning

confidence: 99%

Source Regions of the Interplanetary Magnetic Field and Variability in Heavy-Ion Elemental Composition in Gradual Solar Energetic Particle Events

Tylka

et al. 2013

ApJ

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Gradual solar energetic particle (SEP) events are those in which ions are accelerated to their observed energies by interactions with a shock driven by a fast coronal mass ejection (CME). Previous studies have shown that much of the observed event-to-event variability can be understood in terms of shock speed and evolution in the shock-normal angle. However, an equally important factor, particularly for the elemental composition, is the origin of the suprathermal seed particles upon which the shock acts. To tackle this issue, we (1) use observed solar-wind speed, magnetograms, and the potential-field source-surface model to map the Sun-L1 interplanetary magnetic field (IMF) line back to its source region on the Sun at the time of the SEP observations and (2) then look for a correlation between SEP composition (as measured by Wind and Advanced Composition Explorer at ∼2-30 MeV nucleon −1 ) and characteristics of the identified IMF source regions. The study is based on 24 SEP events, identified as a statistically significant increase in ∼20 MeV protons and occurring in 1998 and 2003-2006, when the rate of newly emergent solar magnetic flux and CMEs was lower than in solar-maximum years, and the field-line tracing is therefore more likely to be successful. We find that the gradual SEP Fe/O is correlated with the field strength at the IMF source, with the largest enhancements occurring when the footpoint field is strong due to the nearby presence of an active region (AR). In these cases, other elemental ratios show a strong charge-to-mass (q/M) ordering (at least on average), similar to that found in impulsive events. Such results lead us to suggest that magnetic reconnection in footpoint regions near ARs bias the heavy-ion composition of suprathermal seed ions by processes qualitatively similar to those that produce larger heavy-ion enhancements in impulsive SEP events. To address potential technical concerns about our analysis, we also discuss efforts to exclude impulsive SEP events from our event sample.

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Cited by 301 publications

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The Solar Energetic Particle Event of 2010 August 14: Connectivity with the Solar Source Inferred from Multiple Spacecraft Observations and Modeling

The Solar Energetic Particle Event of 2010 August 14: Connectivity with the Solar Source Inferred from Multiple Spacecraft Observations and Modeling

Redefining the Boundaries of Interplanetary Coronal Mass Ejections From Observations at the Ecliptic Plane

Source Regions of the Interplanetary Magnetic Field and Variability in Heavy-Ion Elemental Composition in Gradual Solar Energetic Particle Events

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