Figure 4: Variability in the total solar irradiance over the past three decades in comparison with the variance in components of the solar spectral irradiance over solar cycle 23.
From: The solar magnetic activity band interaction and instabilities that shape quasi-periodic variability
(a) The University of Colorado TSI composite10 in comparison with (b) the SOHO/VIRGO TSI over solar cycle 23—the thick vertical dashed line marks the start of the SOHO/VIRGO record used. In both cases, the thick red lines are the 50-day running average over the measurements. While the mean solar minimum to solar maximum change in TSI is ∼1 Wm−2, there is a shorter-period modulation variation visible in the TSI over the entire time frame. That variation, of the same magnitude as the decadal variation, is better defined in solar cycle 23 due to refinement in instrument design and calibration10. (c–e) Percentage variation in different bands (relative to the mean spectrum) of the solar spectral irradiance from the SORCE spacecraft from the far-ultraviolet, ultraviolet SOLSTICE measurements. As we move to shorter wavelengths, the degree of variation in one of the surges in solar radiation increases from a few to 50%. XPS, X-ray photoelectron spectroscopy.
