Latitudinal cosmic ray gradients: Their relation to solar activity asymmetry

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JA02502· OSTI ID:5194880

Swinson, D B ^[1]; Humble, J E ^[2]; Shea, M A; Smart, D F ^[3]

---

1. Univ. of New Mexico, Albuquerque (USA)
2. Univ. of Tasmania, Hobart (Australia)
3. Geophysics Lab., Hanscom AFB, MA (USA)

Data obtained by underground cosmic ray telescopes in the northern and southern hemispheres between 1965 and 1985 are analyzed as a function of the interplanetary magnetic field (IMF) sense to examine the long-term nature of the latitudinal cosmic ray gradient, {gradient}N{sub p}. The nature of this gradient is inferred from the B {times} {gradient} N{sub p} contribution to the solar diurnal cosmic ray anisotropy arising from the interaction between the latitudinal gradient and the IMF B. In an earlier paper, the authors noted a correspondence between the characteristics of the latitudinal gradient and the north-south asymmetry in activity on the Sun during the same period and attempted to explain the result in terms of a combination of two gradients: a north-south symmetrical gradient and a north-south asymmetrical gradient. In this paper, the authors present results showing that asymmetry in activity on the Sun displaces the heliospheric neutral sheet either below or above the Earth (on average), according to the direction of the solar activity asymmetry. This displacement, combined with a latitudinal cosmic ray density gradient that is symmetrical in relation to the neutral sheet, produces a latitudinal cosmic ray gradient that is asymmetrical when viewed from the Earth. The cosmic ray data are consistent with a symmetric (in relation to the neutral sheet) latitudinal cosmic ray density gradient in which the density initially decreases with distance from the neutral sheet and then increases again with increasing distance from the sheet. Additional data from inclined underground cosmic ray telescopes, viewing from 60{degree}N to 50{degree}S, give information on latitudinal gradients further from the neutral sheet.

• OSTI ID: 5194880
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A2; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
ASYMMETRY
ATMOSPHERES
COSMIC RADIATION
COSMIC RAY DETECTION
DATA ANALYSIS
DETECTION
HELIOSPHERE
INTERPLANETARY MAGNETIC FIELDS
IONIZING RADIATIONS
MAGNETIC FIELDS
RADIATION DETECTION
RADIATIONS
SOLAR ATMOSPHERE
SOLAR RADIATION
STELLAR RADIATION
THRESHOLD RIGIDITY
UNDERGROUND FACILITIES