A “loss cone” precursor of an approaching shock observed by a cosmic ray muon hodoscope on October 28, 2003

Munakata, K.; Kuwabara, T.; Yasue, S.; Kato, C.; Akahane, S.; Koyama, M.; Ōhashi, Y.; Okada, Atsushi; Aoki, T.; Mitsui, K.; Kojima, Hiroshi; Bieber, J. W.

doi:10.1029/2004gl021469

Cited by 24 publications

(21 citation statements)

References 5 publications

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“…Forbush decrease (FD) represents the reduction in the intensity of galactic cosmic rays (GCRs) as detected by neutron monitors and muon detectors due to solar wind disturbances (see e.g., Munakata et al 2005;Dumbovic et al 2012;Arunbabu et al 2013;Ahluwalia et al 2014;Belov et al 2014). Both CMEs and CIRs cause a FD, but the amplitude is significantly higher for CMEs than for CIRs (Dumbovic et al 2012;Maričić et al 2014).…”

Section: Forbush Decreasementioning

confidence: 99%

“…However, the study of FDs has been gaining interest in recent times because of the space weather applications. For example, the development of Global Muon Detector Network (GMDN - Munakata et al 2005;Fushishita et al 2010;Rockenbach et al 2011) has greatly enhanced the possibility of forecasting ICME arrival using the network (see e.g., Rockenbach et al 2014 for a review).…”

Section: Forbush Decreasementioning

confidence: 99%

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Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

Gopalswamy

Tsurutani

Yan

2015

Prog. in Earth and Planet. Sci.

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This paper presents an overview of results obtained during the CAWSES-II period on the short-term variability of the Sun and how it affects the near-Earth space environment. CAWSES-II was planned to examine the behavior of the solar-terrestrial system as the solar activity climbed to its maximum phase in solar cycle 24. After a deep minimum following cycle 23, the Sun climbed to a very weak maximum in terms of the sunspot number in cycle 24 (MiniMax24), so many of the results presented here refer to this weak activity in comparison with cycle 23. The short-term variability that has immediate consequence to Earth and geospace manifests as solar eruptions from closed-field regions and high-speed streams from coronal holes. Both electromagnetic (flares) and mass emissions (coronal mass ejections -CMEs) are involved in solar eruptions, while coronal holes result in high-speed streams that collide with slow wind forming the so-called corotating interaction regions (CIRs). Fast CMEs affect Earth via leading shocks accelerating energetic particles and creating large geomagnetic storms. CIRs and their trailing high-speed streams (HSSs), on the other hand, are responsible for recurrent small geomagnetic storms and extended days of auroral zone activity, respectively. The latter leads to the acceleration of relativistic magnetospheric 'killer' electrons. One of the major consequences of the weak solar activity is the altered physical state of the heliosphere that has serious implications for the shock-driving and storm-causing properties of CMEs. Finally, a discussion is presented on extreme space weather events prompted by the 23 July 2012 super storm event that occurred on the backside of the Sun. Many of these studies were enabled by the simultaneous availability of remote sensing and in situ observations from multiple vantage points with respect to the Sun-Earth line.

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Section: Forbush Decreasementioning

confidence: 99%

Section: Forbush Decreasementioning

confidence: 99%

Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

Gopalswamy

Tsurutani

Yan

2015

Prog. in Earth and Planet. Sci.

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“…Recently, a study has demonstrated that modeling the high‐energy cosmic ray density inside the ICME can also be used to determine ICME magnetic field geometry and orientation [ Kuwabara et al , 2004]. Behind the shock (if present) and inside the ICME, there is a cosmic ray density‐depleted region associated with a Forbush decrease [ Cane , 2000; Hofer and Flueckiger , 2000], and that sometimes results in precursory signatures observable upstream of the shock [ Munakata et al , 2005]. Within and around this depleted region, there is a “B × grad(n)” drift flow originating with the particle gyromotion and the density (n) gradient perpendicular to the magnetic field (B).…”

Section: Introductionmentioning

confidence: 99%

Determination of interplanetary coronal mass ejection geometry and orientation from ground‐based observations of galactic cosmic rays

et al. 2009

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[1] We have developed a method for determining interplanetary coronal mass ejection (ICME) geometry from galactic cosmic ray data recorded by the ground-based muon detector network. The cosmic ray density depression inside the ICME, which is associated with a Forbush decrease, is represented by an expanding cylinder that is based on a theoretical model of the cosmic ray particle diffusion. ICME geometry and orientation are deduced from observed time variations of cosmic ray density and density gradient and are compared with those deduced from a magnetic flux rope model. From March 2001 to May 2005, 11 ICME events that produced Forbush decreases >2% were observed, and clear variations of the density gradient due to ICME passage were observed in 8 of 11 events. In five of the eight events, signatures of magnetic flux rope structure (large, smooth rotation of magnetic field) were also seen, and the ICME geometry and orientation deduced from the two methods were very similar in three events. This suggests that the cosmic ray-based method can be used as a complementary method for deducing ICME geometry especially for events where a large Forbush decrease is observed.

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“…These anomalies in the CR variations were recognized a long time ago (Fenton et al, 1959;Blokh, Dorman, and Kaminer, 1959), but over the last few years this particular subject has been intensively investigated (Nagashima et al, 1993;Belov et al, 1995;Belov et al, 2001;Leerungnavarat, Ruffolo, and Bieber, 2003;Munakata et al, 2005;Asipenka et al, 2009). The above-mentioned changes in the behavior of the galactic CRs are observed from one hour up to 20 hours before the shock arrival (Belov et al 1995(Belov et al , 2001 and can be used to forecast the oncoming disturbance and the geomagnetic storm.…”

mentioning

confidence: 99%

“…The neutron-monitor network is a good tool for detecting such anomalies in the pitch angle or longitudinal distribution of CR variations. In recent years, searching for predictors by muon-telescope data has also been developed rather successfully (Munakata et al 2000(Munakata et al , 2005(Munakata et al , 2006Kudela and Storini, 2006). One approach to display the possible precursor effects is the "Ring of Stations" method based on the asymptotic angle distribution of the CR variations which has been used in many studies.…”

mentioning

confidence: 99%

Precursor Effects in Different Cases of Forbush Decreases

et al. 2011

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Over the last few years, the pre-decreases or pre-increases of the cosmic-ray intensity observed before a Forbush decrease, called the precursor effect and registered by the worldwide neutron monitor network, have been investigated for different cases of intense events. The Forbush decreases presented in this particular study were chosen from a list of events that occurred in the time period 1967 -2006 and were characterized by an enhanced first harmonic of cosmic-ray anisotropy prior to the interplanetary disturbance arrival. The asymptotic longitudinal cosmic-ray distribution diagrams for the events under consideration were studied using the "Ring of Stations" method, and data on solar flares, solar-wind speed, geomagnetic indices, and interplanetary magnetic field were analyzed in detail. The results revealed that the use of this method allowed the selection of a large number of events with well-defined precursors, which could be separated into at least three categories, according to duration and longitudinal zone. Finally, this analysis showed that the first harmonic of cosmic-ray anisotropy could serve as an adequate tool in the search for precursors and could also be evidence for them.

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A “loss cone” precursor of an approaching shock observed by a cosmic ray muon hodoscope on October 28, 2003

Cited by 24 publications

References 5 publications

Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

Determination of interplanetary coronal mass ejection geometry and orientation from ground‐based observations of galactic cosmic rays

Precursor Effects in Different Cases of Forbush Decreases

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