An observation of heliospheric magnetic cycle dependence for the integral radial gradient of E > 60 MEV cosmic rays

Journal Article · Sun Sep 01 04:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA01602· OSTI ID:5260826

Webber, W R; Lockwood, J A ^[1]

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1. Univ. of New Hampshire, Durham (United States)

The author find that the magnitudes of the integral radial gradients of > 60 MeV cosmic ray particles as measured between Pioneer 10 (P10) and IMP and between Voyager 2 (V2) and IMP (also P10 and V2) during a period of negative solar magnetic polarity are a strong function of the cosmic ray intensity. These gradients increase from {approximately} 1.5%/AU at the time of peak intensity in 1987 to {approximately} 3%/AU at the times of minimum intensity in 1982 and 1990. During this time a strong radial dependence of the differential radial gradient was also observed, correlated with the appearance of a latitudinal gradient as measured between V2 and V1. In an earlier period of positive polarity from 1977 to 1982 they found practically no dependence of the magnitude of the integral radial gradient on the cosmic ray intensity. This gradient remained at {approximately} 3%/AU during the entire period and no significant radial dependence of the differential gradient was observed. These specific changes in the behavior of the gradient in opposite polarity cycles do not seem to be predicted by either the drift-wavy current sheet or simple diffusion-convection models of the solar modulation, although it is interesting to note that the dependence of the magnitude of the radial gradient on intensity observed during the negative polarity period from 1982 to 1990 is consistent with the predictions of simple diffusion-convection models. These results are discussed in the context of the understanding of the causes for the asymmetry in the 11-year modulation cycles, particularly with regard to how particles enter the heliosphere and how, once inside the heliosphere and how, once inside the heliosphere, they move from the polar to the equatorial regions.

• OSTI ID: 5260826
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A9; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ASYMMETRY
ATMOSPHERES
CORRELATIONS
COSMIC RADIATION
COSMIC RAY PROPAGATION
HELIOSPHERE
IMP SATELLITES
INTERPLANETARY SPACE
IONIZING RADIATIONS
MAGNETIC FIELDS
MAIN SEQUENCE STARS
MATHEMATICAL MODELS
MODULATION
PIONEER SPACE PROBES
RADIATIONS
SATELLITES
SOLAR ATMOSPHERE
SPACE
SPACE VEHICLES
STARS
SUN
VEHICLES
VOYAGER SPACE PROBES