Multi-Spacecraft Observations: Stream Interactions and Associated Structures

Jian, L. K.; Russell, C. T.; Luhmann, J. G.; Galvin, A. B.; MacNeice, P. J.

doi:10.1007/s11207-009-9445-3

Cited by 39 publications

(35 citation statements)

References 29 publications

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“…At 1 AU, Jian et al (2006) have found that only 24% of SIRs have shocks. These shocks are still in a phase of building up at 1 AU, and the shocks are small and transient structures, as observed with multi spacecraft (Jian et al 2009). The sources of fast streams are typically large and stable coronal holes.…”

Section: Introductionmentioning

confidence: 63%

Mean shape of interplanetary shocks deduced from in situ observations and its relation with interplanetary CMEs

Janvier

Démoulin

Dasso

2014

A&A

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Context. Shocks are frequently detected by spacecraft in the interplanetary space. However, the in situ data of a shock do not provide direct information on its overall properties even when a following interplanetary coronal mass ejection (ICME) is detected. Aims. The main aim of this study is to constrain the general shape of ICME shocks with a statistical study of shock orientations. Methods. We first associated a set of shocks detected near Earth over 10 years with a sample of ICMEs over the same period. We then analyzed the correlations between shock and ICME parameters and studied the statistical distributions of the local shock normal orientation. Supposing that shocks are uniformly detected all over their surface projected on the 1 AU sphere, we compared the shock normal distribution with synthetic distributions derived from an analytical shock shape model. Inversely, we derived a direct method to compute the typical general shape of ICME shocks by integrating observed distributions of the shock normal. Results. We found very similar properties between shocks with and without an in situ detected ICME, so that most of the shocks detected at 1 AU are ICME-driven even when no ICME is detected. The statistical orientation of shock normals is compatible with a mean shape having a rotation symmetry around the Sun-apex line. The analytically modeled shape captures the main characteristics of the observed shock normal distribution. Next, by directly integrating the observed distribution, we derived the mean shock shape, which is found to be comparable for shocks with and without a detected ICME and weakly affected by the limited statistics of the observed distribution. We finally found a close correspondence between this statistical result and the leading edge of the ICME sheath that is observed with STEREO imagers. Conclusions. We have derived a mean shock shape that only depends on one free parameter. This mean shape can be used in various contexts, such as studies for high-energy particles or space weather forecasts.

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Section: Introductionmentioning

confidence: 63%

Mean shape of interplanetary shocks deduced from in situ observations and its relation with interplanetary CMEs

Janvier

Démoulin

Dasso

2014

A&A

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“…1. In May 2007, the three spacecraft were very close, but the shocks driven by the same SIR were missed by one or two spacecraft, suggesting SIRdriven shocks were still in development at 1 AU and they were small or transient structures [e.g., 16,17]. In April -May 2008, when L1 and one STEREO spacecraft were separated by ~25 o in longitude, we started to see the absence of one SIR at one spacecraft.…”

Section: Survey Of Large-scale Solar Wind Structuresmentioning

confidence: 96%

Solar wind observations at STEREO: 2007 - 2011

Jian¹,

Russell²,

Luhmann³

et al. 2013

AIP Conference Proceedings

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“…Nevertheless, the PFSS model has proven very successful in identifying the open-field regions at the Sun and the largescale heliospheric structures such as magnetic sectors (e.g., Neugebauer et al 1998Neugebauer et al , 2002Wang & Sheeley 2006;Jian et al 2009;Lee et al 2009). More stringent tests of the PFSS model have come from mapping studies of impulsive SEP events (Nitta et al 2006;Nitta & DeRosa 2008;Rust et al 2008;MacNeice et al 2011).…”

Section: Sep Intervals and Imf Source Region Characterizationmentioning

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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Multi-Spacecraft Observations: Stream Interactions and Associated Structures

Cited by 39 publications

References 29 publications

Mean shape of interplanetary shocks deduced from in situ observations and its relation with interplanetary CMEs

Mean shape of interplanetary shocks deduced from in situ observations and its relation with interplanetary CMEs

Solar wind observations at STEREO: 2007 - 2011

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

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