Rotation of the Earth, solar activity and cosmic ray intensity
- 1CEREGE, Aix-Marseille Université, CNRS, IRD, Collège de France, 13545 Aix-en-Provence, France
- 2Departamento de Geofisica (DGEO), Universidad de Concepción (UDEC), Casilla 160-C, Concepción 4030000, Chile
- *present address: LAM – Laboratoire d'Astrophysique de Marseille, Aix-Marseille Université, CNRS-INSU, 13388 Marseille, France
Abstract. We analyse phase lags between the 11-year variations of three records: the semi-annual oscillation of the length of day (LOD), the solar activity (SA) and the cosmic ray intensity (CRI). The analysis was done for solar cycles 20–23. Observed relationships between LOD, CRI and SA are discussed separately for even and odd solar cycles. Phase lags were calculated using different methods (comparison of maximal points of cycles, maximal correlation coefficient, line of synchronization of cross-recurrence plots). We have found different phase lags between SA and CRI for even and odd solar cycles, confirming previous studies. The evolution of phase lags between SA and LOD as well as between CRI and LOD shows a positive trend with additional variations of phase lag values. For solar cycle 20, phase lags between SA and CRI, between SA and LOD, and between CRI and LOD were found to be negative. Overall, our study suggests that, if anything, the length of day could be influenced by solar irradiance rather than by cosmic rays.