Interplanetary flow systems associated with cosmic ray modulation in 1977–1980

Burlaga, L. F.; McDonald, F. B.; Ness, N. F.; Schwenn, R.; Lazarus, A. J.; Mariani, F.

doi:10.1029/ja089ia08p06579

Cited by 150 publications

(88 citation statements)

References 42 publications

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“…Burlaga et al 1984;Cane 2000). Differences between the shock-associated and no-shock events were studied by Badruddin et al (1986) and Badruddin (1996).…”

Section: Methodsmentioning

confidence: 99%

“…First, the data set was sorted by the type of SWD, i.e., a distinction was made between interplanetary coronal mass ejections (ICME), corotating interaction regions (CIR), and mixed ICME-CIR disturbances (mixed). The distinction between ICMEs and CIRs was made following Burlaga et al (1984), Richardson et al (1996), Cane (2000) and Richardson (2004), whereas the events that showed characteristics of both were denoted as mixed events. Examples of ICME-, CIR-, and mixed-events are presented in Figs.…”

Section: Methodsmentioning

confidence: 99%

“…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%

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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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“…Burlaga et al 1984;Cane 2000). Differences between the shock-associated and no-shock events were studied by Badruddin et al (1986) and Badruddin (1996).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

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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“…Relations between FD magnitudes and the solar wind IMF (Barden, 1973;Iucci et al, 1979a, b;Burlaga et al, 1984;Cane, 1993) and solar wind velocity (Iucci et al, 1979a, b;Belov and Ivanov, 1997) have been studied since long, but the magnitude of the FD and the interplanetary magnetic field (IMF) or the proton velocity V alone have not correlated well. Several studies have shown improved correlations when both the field B and speed V are simultaneously considered.…”

Section: Introductionmentioning

confidence: 99%

Severe geomagnetic storms and Forbush decreases: interplanetary relationships reexamined

Kane

2010

Ann. Geophys.

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Abstract. Severe storms (Dst) and Forbush decreases (FD) during cycle 23 showed that maximum negative Dst magnitudes usually occurred almost simultaneously with the maximum negative values of the B z component of interplanetary magnetic field B, but the maximum magnitudes of negative Dst and B z were poorly correlated (+0.28). A parameter B z (CP) was calculated (cumulative partial B z ) as sum of the hourly negative values of B z from the time of start to the maximum negative value. The correlation of negative Dst maximum with B z (CP) was higher (+0.59) as compared to that of Dst with B z alone (+0.28). When the product of B z with the solar wind speed V (at the hour of negative B z maximum) was considered, the correlation of negative Dst maximum with V B z was +0.59 and with V B z (CP), 0.71. Thus, including V improved the correlations. However, ground-based Dst values have a considerable contribution from magnetopause currents (several tens of nT, even exceeding 100 nT in very severe storms). When their contribution is subtracted from Dst(nT), the residue Dst* representing true ring current effect is much better correlated with B z and B z (CP), but not with V B z or V B z (CP), indicating that these are unimportant parameters and the effect of V is seen only through the solar wind ram pressure causing magnetopause currents. Maximum negative Dst (or Dst*) did not occur at the same hour as maximum FD. The time evolutions of Dst and FD were very different. The correlations were almost zero. Basically, negative Dst (or Dst*) and FDs are uncorrelated, indicating altogether different mechanism.

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“…During the past three decades, modulation research has been primarily focused on understanding and specifying the roles of two of these termsdiffusion and curvature/gradient drift: (1) In the diffusion-centered view, modulation results from the outward propagation, at the solar wind speed, of large steplike decreases in the GCR intensity (McDonald et al 1981;cf., Morrison 1956, andLockwood 1960). The disturbances responsible for these decreases came to be called "merged interaction regions" (MIRs) or "global merged interaction regions" (GMIRs; Burlaga et al 1984Burlaga et al , 1985Burlaga et al , 1993). (2) Alternatively, the approach championed by Jokipii and colleagues (Jokipii et al 1977;Jokipii and Thomas 1981;Kota and Jokipii 1(83) stresses the importance of curvature and gradient drifts of GCRs in the large-scale field of the heliosphere.…”

Section: Introductionmentioning

confidence: 99%

Solar Drivers of 11-yr and Long-Term Cosmic Ray Modulation

2011

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In the current paradigm for the modulation of galactic cosmic rays (GCRs), diffusion is taken to be the dominant process during solar maxima while drift dominates at minima. Observations during the recent solar minimum challenge the pre-eminence of drift: at such times. In 2009, the rv2 GV GCR intensity measured by the Newark neutron monitor increased by "'5% relative to its maximum value two cycles earlier even though the average tilt angle in 2009 was slightly larger than that in 1986 (--,-,20° vs. rv 14°), while solar wind B was significantly lower (rv 3.9 nT vs. "'5.4 nT). A decomposition of the solar wind into high-speed streams, slow solar wind, and coronal mass ejections (CMEs; including postshock flows) reveals that the Sun transmits its message of changing magnetic field (diffusion coefficient) to the heliosphere primarily through CMEs at solar maximum and high-speed streams at solar minimum. Long-term reconstructions of solar wind B are in general agreement for the rv 1900-present interval and can be used to reliably estimate GCR intensity over this period. For earlier epochs, however, a recent lOBe-based reconstruction covering the past"" 10 4 years shows nine abrupt and relatively short-lived drops of B to ;SO nT, with the first of these corresponding to the Sporer minimum. Such dips are at variance with the recent suggestion that B has a minimum or floor value of ""2.8 nT. A floor in solar wind B implies a ceiling in the GCR intensity (a permanent modulation of the local interstellar spectrum) at a given energy/rigidity. The 30-40% increase in the intensity of 2.5 GV electrons observed by Ulysses during the recent solar minimum raises an interesting paradox that will need to be resolved. E.W. Cliver (12Sl) Space Vehicles

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Interplanetary flow systems associated with cosmic ray modulation in 1977–1980

Cited by 150 publications

References 42 publications

Cosmic ray modulation by different types of solar wind disturbances

Cosmic ray modulation by different types of solar wind disturbances

Severe geomagnetic storms and Forbush decreases: interplanetary relationships reexamined

Solar Drivers of 11-yr and Long-Term Cosmic Ray Modulation

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