Cosmic-ray periodicity at 170 days

Abstract

Power-spectral analysis of cosmic-ray indices (CRI) data for the years 1989–1991 shows a 170-day periodicity of cosmic rays. The periodicity is related to a strong magnetic field. Power-

spectral analysis of the long-term periodicity (∼11 years) of the CRI data for the years 1953– 1997 shows that the period 1989 – 1991 is a unique one in the sense of the discussed pronounced periodicity. The 170-day periodicity of cosmic rays was interpreted in the base of six solar rotations (1 SR = 28.3-day periodicity of 10.7 cm solar radio flux) and may be connected to the instability of the solar core.