Multiscale comparative spectral analysis of satellite total solar irradiance measurements from 2003 to 2013 reveals a planetary modulation of solar activity and its nonlinear dependence on the 11 yr solar cycle
Regular Research Article
25 Nov 2013
1Active Cavity Radiometer Irradiance Monitor (ACRIM) Lab, Coronado, CA 92118, USA
2Duke University, Durham, NC 27708, USA
Abstract. Herein we adopt a multiscale dynamical spectral analysis technique to compare and study the dynamical evolution of the harmonic components of the overlapping ACRIMSAT/ACRIM3 (Active Cavity Radiometer Irradiance Monitor Satellite/Active Cavity Radiometer Irradiance Monitor 3), SOHO/VIRGO (Solar and Heliopheric Observatory/Variability of solar Irradiance and Gravity Oscillations), and SORCE/TIM (Solar Radiation and Climate Experiment/Total Irradiance Monitor) total solar irradiance (TSI) records during 2003.15 to 2013.16 in solar cycles 23 and 24. The three TSI time series present highly correlated patterns. Significant power spectral peaks are common to these records and are observed at the following periods: ~ 0.070 yr, ~ 0.097 yr, ~ 0.20 yr, ~ 0.25 yr, ~ 0.30–0.34 yr, and ~ 0.39 yr. Less certain spectral peaks occur at about 0.55 yr, 0.60–0.65 yr and 0.7–0.9 yr. Four main frequency periods at ~ 4.8 days (~ 0.068 yr), ~ 27.3 days (~ 0.075 yr), at ~ 34–35 days (~ 0.093–0.096 yr), and ~ 36–38 days (~ 0.099–0.104 yr) characterize the solar rotation cycle. The amplitude of these oscillations, in particular of those with periods larger than 0.5 yr, appears to be modulated by the ~ 11 yr solar cycle. Similar harmonics have been found in other solar indices. The observed periodicities are found highly coherent with the spring, orbital and synodic periods of Mercury, Venus, Earth and Jupiter. We conclude that solar activity is likely modulated by planetary gravitational and electromagnetic forces acting on the Sun. The strength of the Sun’s response to planetary forcing depends nonlinearly on the state of internal solar dynamics; planetary–Sun coupling effects are enhanced during solar activity maxima and attenuated during minima.