Modeling Quiet Solar Luminosity Variability from TSI Satellite Measurements and Proxy Models during 1980–2018

Abstract

A continuous record of direct total solar irradiance (TSI) observations began with a series of satellite experiments in 1978. This record requires comparisons of overlapping satellite observations with adequate relative precisions to provide useful long term TSI trend information. Herein we briefly review the active cavity radiometer irradiance monitor physikalisch-meteorologisches observatorium davos (ACRIM-PMOD) TSI composite controversy regarding how the total solar irradiance (TSI) has evolved since 1978 and about whether TSI significantly increased or slightly decreased from 1980 to 2000. The main question is whether TSI increased or decreased during the so-called ACRIM-gap period from 1989 to 1992. There is significant discrepancy between TSI proxy models and observations before and after the gap, which requires a careful revisit of the data analysis and modeling performed during the ACRIM-gap period. In this study, we use three recently proposed TSI proxy models that do not present any TSI increase during the ACRIM-gap, and show that they agree with the TSI data only from 1996 to 2016. However, these same models significantly diverge from the observations from 1981 and 1996. Thus, the scaling errors must be different between the two periods, which suggests errors in these models. By adjusting the TSI proxy models to agree with the data patterns before and after the ACRIM-gap, we found that these models miss a slowly varying TSI component. The adjusted models suggest that the quiet solar luminosity increased from the 1986 to the 1996 TSI minimum by about 0.45 W/m2 reaching a peak near 2000 and decreased by about 0.15 W/m2 from the 1996 to the 2008 TSI cycle minimum. This pattern is found to be compatible with the ACRIM TSI composite and confirms the ACRIM TSI increasing trend from 1980 to 2000, followed by a long-term decreasing trend since.

Placing limits on long-term variations in quiet-Sun irradiance and their contribution to total solar irradiance and solar radiative forcing of climate

“…It has been pointed out that because the TSI models do not contain any allowance for changes in the quiet Sun component, taking the difference between the models and the observations can provide evidence of long term changes in the quiet Sun component (Scafetta et al, 2019). Some journal papers have postulated quiet-Sun variations to generate TSI reconstructions that have much larger long-term variations (e.g.…”

A 60‐Year Cycle in the Meteorite Fall Frequency Suggests a Possible Interplanetary Dust Forcing of the Earth's Climate Driven by Planetary Oscillations

“…Besides the hypothesis of a solar irradiance forcing modulated by the planets (e.g., Scafetta, 2010Scafetta, , 2012aScafetta, , 2012bScafetta & Willson, 2013a, 2013b, 2014Scafetta, Willson, et al, 2019), several authors also proposed a corpuscular forcing of the climate. For example, Svensmark et al (2009) and Svensmark et al (2017) suggested that the incoming cosmic ray flux could directly modulate the cloud system.…”

“…Besides the hypothesis of a solar irradiance forcing modulated by the planets (e.g., Scafetta, 2010, 2012a, 2012b; Scafetta & Willson, 2013a, 2013b, 2014; Scafetta, Willson, et al., 2019), several authors also proposed a corpuscular forcing of the climate. For example, Svensmark et al.…”

Changes in Barents Sea Ice Edge Positions in the Last 442 Years. Part 2: Sun, Moon and Planets

“…The peaks at 1750, 1850 and 1950 are well correlated, but the minima are not as deep and flat in the TSI-series as in the BIE-observations. In the Hoyt-Schatten-ACRIM reconstruction [69] (lower panel), the peaks fit better and the minima around 1800, 1900 and 1960 are better reproduced. In both TSI reconstructions the BIE position is too far north after 2000 CE.…”