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Analysis of cosmic-ray intensity data obtained with continuously operating ground-based detectors in the polar regions and elsewhere has revealed several spectacular manifestations of complex three-dimensional flow patterns in the inner solar system. This note exemplifies three of these manifestations which displayed unusual features and emphasizes that significant off-ecliptic anisotropy is a common occurrence. Most of 85 cosmic-ray storms during the minimum and maximum epochs of the current solar cycle were characterized by demonstrable north-south asymmetry. Hence it is almost selfevident that a varying (although often small) intensity gradient perpendicular to the ecliptic plane is an essential feature of all •osmic-ray modulation mechanisms, although its direct measurement remains an exceedingly difficult problem.Although most of the diverse modulation mechanisms that give rise to time variations in the cosmic-ray intensity are generally understood, it has become increasingly obvious that these phenomena cannot be fully accounted for in terms of the observed characteristics of the solar wind and the associated magnetic-field parameters [Pomerantz and D7•ggal, 1971]. The presently recognized problems stem partly from the lack of in situ observations in the regions outside the equatorial plane. Hopefully some information concerning the gross features of the solar-plasma configurations in these regions can be deduced from cosmic-ray measurements at polar stations [Pomerantz, 1970[Pomerantz, , 1971].The detailed procedures and the underlying mathematical techniques for identifying anisotropies in three-dimensional space have been described previously [Nagashima et al., 1968]. For the present purposes, it can be shown that, for intervals in which the magnitude of the north-south asymmetry appreciably exceeds that of longitudinal intensity variations, the fractional change in the cosmic-ray intensity I at station i is given by (AI/I),= A d-B sin X*(•, i) (1) where A and B are constants for a given interval; B equals a sin kj, where ;•j is the latitude defining the direction of the total vector of anisotropy and a is a constant. The latitude of the effective asymptotic direction of viewing k • is given by sin X*(•, i) = f: R(P)P -'r sin X(P) dP (2) f: (e)e ae Here R(P) is the neutron monitor response function, Pt is the threshold rigidity, and X is the asymptotic latitude for particles with rigidity P. Thus, for the proper value of the exponent 7 in the variational spectrum assumed to be of the form kP -•, a plot of (AI/I)• versus sin X • (7, i) should yield a straight line that defines the magnitude of the north-south asymmerry. We have recently shown that, if, instead of the previously mentioned rigorous procedure, a criterion based on differential intensity at two stations is used, erroneous conclusions can result [Duggal and Pomerantz, 1971].A complex cosmic-ray storm that commenced on January 27, 1971, is represented in Figure 1. In this event, the intensity recorded at the southern polar stations (S) was un...
Analysis of cosmic-ray intensity data obtained with continuously operating ground-based detectors in the polar regions and elsewhere has revealed several spectacular manifestations of complex three-dimensional flow patterns in the inner solar system. This note exemplifies three of these manifestations which displayed unusual features and emphasizes that significant off-ecliptic anisotropy is a common occurrence. Most of 85 cosmic-ray storms during the minimum and maximum epochs of the current solar cycle were characterized by demonstrable north-south asymmetry. Hence it is almost selfevident that a varying (although often small) intensity gradient perpendicular to the ecliptic plane is an essential feature of all •osmic-ray modulation mechanisms, although its direct measurement remains an exceedingly difficult problem.Although most of the diverse modulation mechanisms that give rise to time variations in the cosmic-ray intensity are generally understood, it has become increasingly obvious that these phenomena cannot be fully accounted for in terms of the observed characteristics of the solar wind and the associated magnetic-field parameters [Pomerantz and D7•ggal, 1971]. The presently recognized problems stem partly from the lack of in situ observations in the regions outside the equatorial plane. Hopefully some information concerning the gross features of the solar-plasma configurations in these regions can be deduced from cosmic-ray measurements at polar stations [Pomerantz, 1970[Pomerantz, , 1971].The detailed procedures and the underlying mathematical techniques for identifying anisotropies in three-dimensional space have been described previously [Nagashima et al., 1968]. For the present purposes, it can be shown that, for intervals in which the magnitude of the north-south asymmetry appreciably exceeds that of longitudinal intensity variations, the fractional change in the cosmic-ray intensity I at station i is given by (AI/I),= A d-B sin X*(•, i) (1) where A and B are constants for a given interval; B equals a sin kj, where ;•j is the latitude defining the direction of the total vector of anisotropy and a is a constant. The latitude of the effective asymptotic direction of viewing k • is given by sin X*(•, i) = f: R(P)P -'r sin X(P) dP (2) f: (e)e ae Here R(P) is the neutron monitor response function, Pt is the threshold rigidity, and X is the asymptotic latitude for particles with rigidity P. Thus, for the proper value of the exponent 7 in the variational spectrum assumed to be of the form kP -•, a plot of (AI/I)• versus sin X • (7, i) should yield a straight line that defines the magnitude of the north-south asymmerry. We have recently shown that, if, instead of the previously mentioned rigorous procedure, a criterion based on differential intensity at two stations is used, erroneous conclusions can result [Duggal and Pomerantz, 1971].A complex cosmic-ray storm that commenced on January 27, 1971, is represented in Figure 1. In this event, the intensity recorded at the southern polar stations (S) was un...
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