Total Solar Irradiance during the Last Five Centuries

Penza, V.; Berrilli, F.; Bertello, L.; Cantoresi, Matteo; Criscuoli, S.; Giobbi, Piermarco

doi:10.3847/1538-4357/ac8a4b

Cited by 14 publications

(11 citation statements)

References 102 publications

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“…Use of historical photographic data for irradiance reconstructions has so far been rather limited, with only five TSI reconstructions from historical Ca II K observations known to us, namely, by Ambelu et al (2011), Foukal (2012, Penza et al (2022), Xu et al (2021), and Chatzistergos et al (2021a). Ambelu et al (2011), Foukal (2012), and Xu et al (2021 used the photometrically uncalibrated Mt Wilson, Mt Wilson, and Kodaikanal Ca II K data, respectively to reconstruct TSI variations with a linear regression model.…”

Section: Irradiance Reconstructionmentioning

confidence: 99%

“…These studies also did not account for the various instrumental changes affecting the data, thus rendering their results highly uncertain. Penza et al (2022) used the plage area composite seriequiet Sun or active regions separately. All of these factors lets by Chatzistergos et al (2019b) to reconstruct TSI over the last five centuries with an empirical model.…”

Section: Irradiance Reconstructionmentioning

confidence: 99%

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Full-disc Ca ii K observations—A window to past solar magnetism

Chatzistergos

Krivova

Ermolli

2022

Front. Astron. Space Sci.

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Full-disc observations of the Sun in the Ca ii K line provide one of the longest collections of solar data. First such observations were made in 1892 and since then various sites around the world have carried out regular observations, with Kodaikanal, Meudon, Mt Wilson, and Coimbra being some of the most prominent ones. By now, Ca ii K observations from over 40 different sites allow an almost complete daily coverage of the last century. Ca ii K images provide direct information on plage and network regions on the Sun and, through their connection to solar surface magnetic field, offer an excellent opportunity to study solar magnetism over more than a century. This makes them also extremely important, among others, for solar irradiance reconstructions and studies of the solar influence on Earth’s climate. However, these data also suffer from numerous issues, which for a long time have hampered their analysis. Without properly addressing these issues, Ca ii K data cannot be used to their full potential. Here, we first provide an overview of the currently known Ca ii K data archives and sources of the inhomogeneities in the data, before discussing existing processing techniques, followed by a recap of the main results derived with such data so far.

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Section: Irradiance Reconstructionmentioning

confidence: 99%

Section: Irradiance Reconstructionmentioning

confidence: 99%

Full-disc Ca ii K observations—A window to past solar magnetism

Chatzistergos

Krivova

Ermolli

2022

Front. Astron. Space Sci.

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“…Semi-empirical models rely on solar observations to determine the location and area covered by magnetic features, while solar model atmospheres and spectral synthesis codes are used to calculate the brightness spectra of these features (e.g. Fligge et al 1998;Ermolli 2001;Ermolli et al 2003Ermolli et al , 2011Krivova et al 2003Krivova et al , 2007Krivova et al , 2009bKrivova et al , 2010Krivova et al , 2011Penza et al 2003;Fontenla et al 2006Fontenla et al , 2011Wenzler et al 2006;Crouch et al 2008;Haberreiter et al 2008Haberreiter et al , 2014Shapiro et al 2011;Vieira et al 2011;Ball et al 2012;Bolduc et al 2014;Dasi-Espuig et al 2014, 2016Wu et al 2018;Chatzistergos et al 2021a). Both empirical and semi-empirical models have free parameters that need to be set by comparison to direct TSI data.…”

Section: Irradiance Models and Reconstructionsmentioning

confidence: 99%

“…. 2011; Penza et al 2003;Fontenla & Landi 2018;Puiu 2019;Chatzistergos et al 2020aChatzistergos et al , 2021b, which do not require photometric calibration and suffer from considerably fewer artefacts than the historical data. These studies are particularly important to ascertain the ability of Ca ii K data to be used for accurate irradiance reconstructions.…”

Section: Ca II K Observationsmentioning

confidence: 99%

“…Use of photographic Ca ii K data for irradiance reconstructions has been significantly more limited than that of CCD-based ones. To our knowledge, the only TSI reconstructions from photographic Ca ii K data are those by Ambelu et al (2011), Foukal (2012, Xu et al (2021), Penza et al (2022), andChatzistergos et al (2021a). Thereby, Ambelu et al (2011), Foukal (2012), and Xu et al (2021 used linear regression models to reconstruct TSI variations, which limits their reliability.…”

Section: Ca II K Observationsmentioning

confidence: 99%

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Long-term changes in solar activity and irradiance

Chatzistergos¹,

Krivova²,

Yeo³

2023

Preprint

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The Sun is the main energy source to Earth, and understanding its variability is of direct relevance to climate studies. Measurements of total solar irradiance (TSI) exist since 1978, but this is too short compared to climate-relevant time scales. Coming from a number of different instruments, these measurements require a cross-calibration, which is not straightforward, and thus several composite records have been created. All of them suggest a marginally decreasing trend since 1996. Most composites also feature a weak decrease over the entire period of observations, which is also seen in observations of the solar surface magnetic field and is further supported by Ca ii K data. Some inconsistencies, however, remain and overall the magnitude and even the presence of the long-term trend remain uncertain. Different models have been developed, which are used to understand the irradiance variability over the satellite period and to extend the records of solar irradiance back in time. Differing in their methodologies, all models require proxies of solar magnetic activity as input. The most widely used proxies are sunspot records and cosmogenic isotope data on centennial and millennial time scale, respectively. None of this, however, offers a sufficiently good, independent description of the long-term evolution of faculae and network responsible for solar brightening. This leads to significant uncertainties in the amplitude of the long-term changes in solar irradiance. Here we review recent efforts to improve irradiance reconstructions on time scales longer than the solar cycle and to reduce the existing uncertainty in the magnitude of the long-term variability. In particular, we highlight the potential of using 3D magnetohydrodynamical simulations of the solar atmosphere as input to more physical irradiance models and of historical full-disc Ca ii K observations encrypting direct facular information back to 1892.

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A Discussion of Implausible Total Solar-Irradiance Variations Since 1700

Chatzistergos

2024

Sol Phys

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The Sun plays a role in influencing Earth’s climate, making it important to have accurate information about variations in the Sun’s radiative output. Models are used to recover total solar-irradiance (TSI) variations in the past when direct space-based measurements are not available. One of the most cryptic such TSI reconstructions is the one by (J. Geophys. Res. 98, 18, 1993, HS93). The rather vague description of the model methodology, the arbitrary selection of solar indices it employs, and the short overlap between the HS93 series and directly measured TSI values has hindered any evaluation of the performance of this model to this day. Here, we aim at rectifying this by updating the HS93 model with new input data. In this way we are also contributing in the discussion on the possible long-term changes in solar irradiance.We find that the analysis by HS93 included a number of erroneous processing steps that led to an artificial increasing trend towards the end of the reconstructed TSI series as well as shifting the peak of the TSI in the mid-twentieth century back in time by about 11 years. Furthermore, by using direct measurements of the TSI we determined that the free parameter of the model, the magnitude of variations (here defined as percentage variations of the difference between the maximum to minimum values), is optimal when it is minimised (being ≤0.05%). This is in stark contrast to the high magnitude of variations, of 0.25%, that was imposed by HS93. However, our result is consistent with more recent estimates, such as those from the Spectral And Total Irradiance REconstruction (SATIRE) model and Naval Research Laboratory TSI (NRLTSI), which were used by the Intergovernmental Panel on Climate Change (IPCC). Overall, we find that the previously reported agreement of the HS93 TSI series to temperature on Earth was purely due to improper analysis and artefacts of the processing.

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Total Solar Irradiance during the Last Five Centuries

Cited by 14 publications

References 102 publications

Full-disc Ca ii K observations—A window to past solar magnetism

Full-disc Ca ii K observations—A window to past solar magnetism

Long-term changes in solar activity and irradiance

A Discussion of Implausible Total Solar-Irradiance Variations Since 1700

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