Determination of short-period terms of total solar irradiance

摘要

In addition to the evident 11-year periodic changes, Total solar irradiance (TSI) also has some short-period processes. We carried out the wavelet analysis for TSI observational series and its inter-annual time series that is filtered out components less than 2 years and more than 8 years . Whether the wavelet graph or the global wavelet power spectrum, the results significantly show that there is a short period about 5.3 years, and its length and intensity both vary with time. Specifically, the strength of this period varies with the 11-year cycle change, showing pronounced characteristics of peak strength and valley weakness. Moreover, the amplitude of these low-frequency fraction results indicates different TSI variation properties. Under each solar cycle, the sum of the power spectrum density of the 3-6 year period terms reflects that the energy value of the short period is concentrated in that range. When the 11-year cycle is intensive, the 3-6 year period also becomes intensive in TSI. And the total spectral intensity of TSI will be concentrated in that short-period terms.