High-speed solar-wind streams and galactic cosmic-ray modulation

Iucci, N.; Parisi, M.; Storini, M.; Villoresi, G.

doi:10.1007/bf02558283

Cited by 107 publications

(56 citation statements)

References 12 publications

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“…Because the pattern of the SW and IMF disturbances is different for these two phenomena, they can be readily identified in the in-situ measurements (see e.g. Iucci et al 1979;Burlaga et al 1984;Cane 2000;Richardson 2004). With respect to this, we note that interaction of these two phenomena leads to the occurrence of complex events (Belov et al 2001) that represent a separate class of SWDs.…”

Section: Introductionmentioning

confidence: 99%

“…Iucci et al 1979;Badruddin et al 1986;Badruddin 1996;Singh & Badruddin 2007), statistical analysis (e.g. Cane et al 1996;Richardson et al 1996;Belov et al 2001;Čalogović et al 2009;Chilingarian & Bostanjyan 2010) and case-studies (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Cane et al (1996) declared speed as a poor predictor of depression amplitude, whereas Chilingarian & Bostanjyan (2010) found a strong correlation between the two. Another aspect of CR modulation, the time profile, was found to be related to the speed for both CIRs (Iucci et al 1979) and ICMEs (Badruddin et al 1986;Penna & Quillen 2005), but some questions still remain open (see, e.g. Lockwood et al 1986;Jämsén et al 2007).…”

Section: Introductionmentioning

confidence: 99%

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Cosmic ray modulation by different types of solar wind disturbances

Dumbović

Vršnak

Čalogović

et al. 2012

A&A

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Context. Solar wind disturbances such as interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs) cause short-term cosmic ray depressions, generally denoted as Forbush decreases. Aims. We conduct a systematic statistical study of various aspects of Forbush decreases. The analysis provides empirical background for physical interpretations of short-term cosmic ray modulations. Methods. Firstly, we analyzed the effects of different types of solar wind disturbances, and secondly, we focused on the phenomenon of over-recovery (the return of the cosmic ray count to a value higher than the pre-decrease level). The analysis is based on groundbased neutron monitor data and the solar wind data recorded by the Advanced Composition Explorer. The correlations between various cosmic ray depressions and solar wind parameters as well as their statistical significance are analyzed in detail. In addition, we performed a normalized superposed epoch analysis for depressions and magnetic field enhancements. Results. The analysis revealed differences in the relationship between different solar wind disturbances and cosmic ray depression parameters. The amplitude of the depression for ICMEs was found to correlate well with the amplitudes of magnetic field strength and fluctuations, whereas for CIRs we found only the correlation between the amplitude of the depression and the solar wind disturbance dimension proxy vt B . Similar behavior was found for shock and no-shock events, respectively. The CIR/ICME composites show a specific behavior that is a mixture of both ICMEs and CIRs. For all analyzed categories we found that the duration of the depression correlates with the duration of the solar wind disturbance. The analysis of the over-recovery showed that there is no straightforward relationship to either "branching-effect" or geomagnetic effects, therefore we propose a scenario where the "branching-effect" is caused by several factors and is only indirectly related to the over-recovery.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cosmic ray modulation by different types of solar wind disturbances

Dumbović

Vršnak

Čalogović

et al. 2012

A&A

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“…The solar wind velocity determines two components of the cosmic ray modulation mechanism: the convection and the adiabatic energy changes. The high velocity solar wind fluxes associated with coronal holes give rise to both isotropic and anisotropic variations in cosmic ray intensity (Iucci et al, 1979;Kaminer et al, 1981). Changes of the solar wind velocity near the Earth may have not only local but also the global character (Sheeley et al, 1991;Richardson et al, 1999).…”

Section: Resultsmentioning

confidence: 99%

Modulation of cosmic rays at different cutoff rigidity

Agarwal

Mishra

2008

Braz. J. Phys.

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The present work deals with the study of first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period [1981][1982][1983][1984][1985][1986][1987][1988][1989][1990][1991][1992][1993] for Deep River and Inuvik neutron monitoring stations having mid and low cutoff rigidity. The amplitude of first harmonic remains high for Deep River having mid cutoff rigidity as compared to Inuvik neutron monitor having low cutoff rigidity on quiet days. The diurnal amplitude significantly decreases and phase shifts towards an earlier time during solar activity minimum years at both Deep River and Inuvik. The amplitude of second harmonic significantly enhanced during solar activity minimum as well as maximum at Deep River and remains low during solar activity maximum at Inuvik, whereas the phase shifts towards an earlier time during solar maximum for both the stations. The amplitude of the third harmonic significantly enhanced during solar activity minimum at Deep River and on solar activity minimum at Inuvik, whereas the phase does not show any significant characteristics and fluctuates quite frequently. The amplitude of semi/tri-diurnal anisotropy has a good positive correlation, while the others (i.e. amplitude and phase) have very weak correlation with solar wind velocity on quiet days at Deep River station during 1981-1993. The solar wind velocity significantly remains in the range 350 to 425 km/s i.e. being nearly average on quiet days. The amplitude and direction of the anisotropy on quiet days are weakly dependent on high-speed solar wind streams for two neutron monitoring station of mid and low cutoff rigidity threshold. The amplitude as well as direction of second harmonic has a good anti-correlation with IMF Bz and the product V x Bz on quiet days at Deep River station. However, the direction of second and third harmonic has a good anti-correlation with IMF Bz and the product V x Bz on quiet days at Inuvik station.

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“…These depressions are characterized by maximum GCR flux decreases of 30% at 100 MeV n −1 and are associated with the passage of interplanetary counterparts of coronal mass ejections. Recurrent depressions are caused by corotating highspeed solar wind streams (see Iucci et al 1979, for instance). Quasi-periodicities of 27 days, 13.5 days, and 9 days, correlated with the Sun rotation period (27.28 days for an Earth observer) and higher harmonics, are observed in the cosmic-ray flux, in the solar wind plasma, in the interplanetary magnetic field (IMF), and in the geomagnetic activity indices (Čalogović et al 2009;Emery et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Energy Dependence of Recurrent Galactic Cosmic-Ray Flux Depressions and of a Forbush Decrease with LISA Pathfinder

Armano

Audley

Baird

et al. 2018

ApJ

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Galactic cosmic-ray (GCR) energy spectra observed in the inner heliosphere are modulated by the solar activity, the solar polarity and structures of solar and interplanetary origin. A high counting rate particle detector (PD) aboard LISA Pathfinder, meant for subsystems diagnostics, was devoted to the measurement of GCR and solar energetic particle integral fluxes above 70 MeV n −1 up to 6500 counts s −1 . PD data were gathered with a sampling time of 15 s. Characteristics and energy dependence of GCR flux recurrent depressions and of a Forbush decrease dated 2016 August 2 are reported here. The capability of interplanetary missions, carrying PDs for instrument performance purposes, in monitoring the passage of interplanetary coronal mass ejections is also discussed.

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High-speed solar-wind streams and galactic cosmic-ray modulation

Cited by 107 publications

References 12 publications

Cosmic ray modulation by different types of solar wind disturbances

Cosmic ray modulation by different types of solar wind disturbances

Modulation of cosmic rays at different cutoff rigidity

Characteristics and Energy Dependence of Recurrent Galactic Cosmic-Ray Flux Depressions and of a Forbush Decrease with LISA Pathfinder

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