Origin of transient north-south anisotropy of cosmic rays

Journal Article · Fri Oct 01 04:00:00 EDT 1976 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA081i028p05032· OSTI ID:7344838

Duggal, S P; Pomerantz, M A

A comprehensive analysis of the transient north-south anisotropy that is a characteristic feature of Forbush decreases has revealed that the direction of axial anisotropy is determined by the inclination of the associated interplanetary shock wave with respect to the ecliptic plane. The study included all recorded cosmic ray events (15) for which the sense of the anisotropy vector could be determined by a rigorous statistical procedure and for which the associated shock orientation is known. In contrast, similar examination of the same set of events showed that there is no correlation between the sense of the north-south anisotropy and either the heliolatitude of the associated solar flare or the inclination of the interplanetary magnetic field. An additional investigation of the collection of heretofore puzzling events during which the direction of anisotropy flips suddenly has shown that the reversal is associated with the arrival of a second shock, presumably having an inclination that is opposite to that of the earlier one associated with the onset of the Forbush decrease. These results provide new insight into the key role played by shocks in the transient modulation mechanism. (AIP)

• Research Organization: Bartol Research Foundation of the Franklin Institute, Swarthmore, Pennsylvania 19081
• OSTI ID: 7344838
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 81:28; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
640107 -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ASYMMETRY
COSMIC RAY PROPAGATION
FORBUSH DECREASE
INTERPLANETARY MAGNETIC FIELDS
INTERPLANETARY SPACE
MAGNETIC FIELDS
NORTH-SOUTH ASYMMETRY
SHOCK WAVES
SPACE