THE SOLAR AND COSMIC RAY SYNODIC PERIODICITY (1969--1998)

Antalova, A. (1), Kudela, K. (1) and Rybak J. (2)

(1) Institute of the Experimental Physics, Watson street 47, 043 53 Kosice,
(2) Astronomical Institute, 059 60 Tatranská Lomnica, The Slovak Republic

The synodic recurrence of the Mt. Wilson plage index (MPSI) and the Calgary cosmic ray (CR) intensity is investigated, using the wavelet power spectra in the range of 18-38 days, during the last three solar cycles. The unique temporal coincidence between the quasi--synodic MPSI and the CR periods is detected in 1978-1982 years (the 21st solar cycle). In the 22nd cycle there is very strong MPSI synodic recurrence, from 1989.5 to 1990.5, but it is absent in the CR data. In 1992.5-1993.5 years the MPSI and CR recurrence phenomenon is in good accordance with the solar wind speed and cosmic ray modulation as measured during the first Ulysses passage around the Sun. The Gnevyshev gap is present in the 27-day recurrence of CR, in agreement with Kudela et al. (1999).