Investigation The Periodicity Of Solar Magnetic Fields And Relation Of Them With Total Solar Irradiance

The Sun is the only star which supplies the Earth with energy. It drives almost every known physical and biological cycle in Earth system, and maintains the suitable living environment of all the life on the Earth. Consequently, studying the solar activity and variational rule are of significance and needed. In this article, we mainly investigate the periodicity of the solar magnetic fields as well as the relation of solar magnetic fields with total solar irradiance at time scale of a solar cycle, the results as follows,1, A full-disk solar magnetogram has been measured each day since 1970 January 19, and the daily Magnetic Plage Strength Index(MPSI) and the daily Mount Wilson Sunspot Index(MWSI) were calculated for each magnetogram at the Mount Wilson Observatory. MPSI should represent the activity of the weak magnetic fields on the solar full disk, while MWSI should indicate the strong magnetic field activity on the disk。 The MPSI and MWSI are used to investigate the periodicity of the solar full-disk magnetic activity through autocorrelation analyses. Just two periods, the solar cycle and the rotation cycle, are determined in both the MPSI(the solar full-disk weak magnetic field activity) and MWSI(the solar full-disk strong magnetic field activity) with no annual signal found.The solar cycle for MPSI(10.83 yr) is found to be obviously longer than that for MWSI(9.77 yr). The rotation cycle is determined to be 26.8 ± 0.63 sidereal days for MPSI and 27.4 ± 2.4 sidereal days for MWSI. The rotation cycle length for MPSI is found to fluctuate around 27 days within a very small amplitude,but for MWSI it obviously temporally varies with a rather large amplitude. The rotation cycle for MWSI seems longer near solar minimum than at solar maximum. Cross-correlation analyses of daily MPSI and MWSI are carried out, and it is inferred that the MPSI components partly come from relatively early MWSI measurements;2,A new Ensemble Empirical Mode Decomposition(EEMD) analysis is utilized to extract the Intrinsic Mode Functions(IMFs) of Solar Mean Magnetic Field(SMMF) observed at Wilcox Solar Observatory of the Stanford University from 1975 to 2014, and then we analyze the periods of these IMFs as well as the relation of IMFs(SMMF) with some solar activity indices. The two special rotation cycles 26.6 and 28.5 days should be derived from different magnetic flux elements in SMMF. The rotation cycle 26.6 days should be derived from the weak magnetic flux element in SMMF, while the rotation cycle 28.5 days is derived from the strong magnetic flux element if SMMF. Furthermore, The two rotation periods of the structure of interplanetary magnetic field near the ecliptic plane are essentially related with weak and strong magnetic flux elements in SMMF,respectively. The rotation cycle of weak magnetic flux in SMMF did not vary over the last 40 years, because the weak magnetic flux element derived from the weak magnetic activity on the full disk is not influenced by latitudinal migration.Neither the internal rotation of the Sun nor the solar magnetic activity on the disk(including the solar polar fields) causes the annual variation of SMMF. The variation of SMMF at time scales of a solar cycle is more related with weak magnetic activity on the full solar disk;3, The PMOD Total Solar Irradiance(TSI), ACRIM TSI and RMIB TSI are three typical TSI composites. Magnetic Plage Strength Index(MPSI) and Mount Wilson Sunspot Index(MWSI) should indicate the weak and strong magnetic field activity on the soar full disk, respectively. Cross Correlation(CC) analysis of MWSI with three TSI composites shows that TSI should be weakly correlated with MWSI, and not be in phase with MWSI at time scale of solar cycles.The Wavelet Coherence(WTC) and Partial Wavelet Coherence(PWC) of TSI with MWSI indicate that the inter-solar-cycle variation of TSI is also not related solar strong magnetic field activity, which is represented by MWSI. However, CC analysis of MPSI with three TSI composites indicates that TSI should be moderately correlated and accurately in phase with MPSI at time scale of solar cycles,and that the statistical significant test indicates that the correlation coefficient of three TSI composites with MPSI is statistically significantly higher than that of three TSI composites with MWSI. Furthermore, the Cross Wavelet Transform(XWT) and WTC of TSI with MPSI show that the TSI is high related and actually in phase with MPSI at time scale of a solar cycle as well. Consequently,the CC analysis, XWT and WTC indicate that the solar weak magnetic activity on the full disk, which is represented by MPSI, dominates the inter-solar-cycle variation of TSI.