Reconstruction of solar irradiance
variations in cycle 23: 
Is solar surface magnetism the cause?

Krivova, N. A.; Solanki, S. K.; Fligge, M.; Unruh, Y. C.

doi:10.1051/0004-6361:20030029

Cited by 271 publications

(416 citation statements)

References 16 publications

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“…On decadal to centennial timescales, SATIRE reproduces observations such as the composite of the Lyman-α line at 121.6 nm (since 1947, Woods et al, 2000), the measured solar photospheric magnetic flux (since 1967), the empirically reconstructed solar open magnetic flux (since 1845, Lockwood et al, 2014), and the 44 Ti activity in stony meteorites (Krivova et al, 2010;Vieira et al, 2011;Yeo et al, 2014). SATIRE and NRLSSI2 are internally consistent, in the sense that the integral of the modeled spectral irradiances equals the TSI.…”

Section: Satirementioning

confidence: 54%

“…The SATIRE (spectral and total irradiance reconstruction) family of semi-empirical models assumes that the changes in the solar spectral irradiance are driven by the evolution of the photospheric magnetic field (Fligge et al, 2000;Krivova et al, 2003Krivova et al, , 2011. The model makes use of the calculated intensity spectra of the quiet Sun, faculae, and sunspots generated from model solar atmospheres with a radiative transfer code (Unruh et al, 1999).…”

Section: Satirementioning

confidence: 99%

“…The implementation of SATIRE employing solar images in visible light and solar magnetograms (magnetic field intensity and polarity) is termed SATIRE-S (Wenzler et al, 2005;Ball et al, 2012;Yeo et al, 2014), and that based on the sunspot number (SSN) is SATIRE-T (Krivova et al, 2010). Individual records are accessible at http://www2.mps.mpg.…”

Section: Satirementioning

confidence: 99%

“…Prior to 1974 the CMIP6 SATIRE data were calculated with the SATIRE-T model (Krivova et al, 2010), although this was done using annual SSN (Version 1) instead of daily Group SSN (GSSN) (Hoyt and Schatten, 1998) while keeping all other inputs (including sunspot area) identical to the original version. SSI variability on subannual timescales, taken from the SATIRE-T model, was added afterwards.…”

Section: Satirementioning

confidence: 99%

“…In this context, and for the time being, the most reasonable approach (in a maximum-likelihood sense) consists of averaging their reconstructions, weighted by their uncertainty. Since, in addition, we are lacking uncertainties that can be meaningfully compared, our current recommendation is to simply take the arithmetic mean of the two model datasets: (i) the empirical model NRLTSI2 and NRLSSI2 (Coddington et al, 2016) and (ii) the semi-empirical model SATIRE (Yeo et al, 2014;Krivova et al, 2010). Note that multimodel averaging is a widely used practice in climate modeling (e.g., Smith et al, 2013).…”

Section: Cmip6-recommended Solar Irradiance Forcingmentioning

confidence: 99%

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Solar forcing for CMIP6 (v3.2)

et al. 2017

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Abstract. This paper describes the recommended solar forcing dataset for CMIP6 and highlights changes with respect to CMIP5. The solar forcing is provided for radiative properties, namely total solar irradiance (TSI), solar spectral irradiance (SSI), and the F10.7 index as well as particle forcing, including geomagnetic indices Ap and Kp, and ionization rates to account for effects of solar protons, electrons, and galactic cosmic rays. This is the first time that a recommendation for solar-driven particle forcing has been provided for a CMIP exercise. The solar forcing datasets are provided at daily and monthly resolution separately for the CMIP6 preindustrial control, historical (1850CMIP6 preindustrial control, historical ( -2014, and future (2015-2300) simulations. For the preindustrial control simulation, both constant and time-varying solar forcing components are provided, with the latter including variability on 11-year and shorter timescales but no long-term changes. For the future, we provide a realistic scenario of what solar behavior could be, as well as an additional extreme Maunderminimum-like sensitivity scenario. This paper describes the forcing datasets and also provides detailed recommendations as to their implementation in current climate models.For the historical simulations, the TSI and SSI time series are defined as the average of two solar irradiance models that are adapted to CMIP6 needs: an empirical onePublished by Copernicus Publications on behalf of the European Geosciences Union. A new and lower TSI value is recommended: the contemporary solar-cycle average is now 1361.0 W m −2 . The slight negative trend in TSI over the three most recent solar cycles in the CMIP6 dataset leads to only a small global radiative forcing of −0.04 W m −2 . In the 200-400 nm wavelength range, which is important for ozone photochemistry, the CMIP6 solar forcing dataset shows a larger solar-cycle variability contribution to TSI than in CMIP5 (50 % compared to 35 %).We compare the climatic effects of the CMIP6 solar forcing dataset to its CMIP5 predecessor by using timeslice experiments of two chemistry-climate models and a reference radiative transfer model. The differences in the long-term mean SSI in the CMIP6 dataset, compared to CMIP5, impact on climatological stratospheric conditions (lower shortwave heating rates of −0.35 K day −1 at the stratopause), cooler stratospheric temperatures (−1.5 K in the upper stratosphere), lower ozone abundances in the lower stratosphere (−3 %), and higher ozone abundances (+1.5 % in the upper stratosphere and lower mesosphere). Between the maximum and minimum phases of the 11-year solar cycle, there is an increase in shortwave heating rates (+0.2 K day −1 at the stratopause), temperatures (∼ 1 K at the stratopause), and ozone (+2.5 % in the upper stratosphere) in the tropical upper stratosphere using the CMIP6 forcing dataset. This solar-cycle response is slightly larger, but not statistically significantly different from that for the CMIP5 forcing dataset.CMIP6 models wi...

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Section: Satirementioning

confidence: 54%

Section: Satirementioning

confidence: 99%

Section: Satirementioning

confidence: 99%

Section: Satirementioning

confidence: 99%

Section: Cmip6-recommended Solar Irradiance Forcingmentioning

confidence: 99%

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Solar forcing for CMIP6 (v3.2)

et al. 2017

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UV solar irradiance in observations and the NRLSSI and SATIRE‐S models

et al. 2015

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Total solar irradiance and UV spectral solar irradiance has been monitored since 1978 through a succession of space missions. This is accompanied by the development of models aimed at replicating solar irradiance by relating the variability to solar magnetic activity. The Naval Research Laboratory Solar Spectral Irradiance (NRLSSI) and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE‐S) models provide the most comprehensive reconstructions of total and spectral solar irradiance over the period of satellite observation currently available. There is persistent controversy between the various measurements and models in terms of the wavelength dependence of the variation over the solar cycle, with repercussions on our understanding of the influence of UV solar irradiance variability on the stratosphere. We review the measurement and modeling of UV solar irradiance variability over the period of satellite observation. The SATIRE‐S reconstruction is consistent with spectral solar irradiance observations where they are reliable. It is also supported by an independent, empirical reconstruction of UV spectral solar irradiance based on Upper Atmosphere Research Satellite/Solar Ultraviolet Spectral Irradiance Monitor measurements from an earlier study. The weaker solar cycle variability produced by NRLSSI between 300 and 400 nm is not evident in any available record. We show that although the method employed to construct NRLSSI is principally sound, reconstructed solar cycle variability is detrimentally affected by the uncertainty in the SSI observations it draws upon in the derivation. Based on our findings, we recommend, when choosing between the two models, the use of SATIRE‐S for climate studies.

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EMPIRE: A robust empirical reconstruction of solar irradiance variability

2017

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We present a new empirical model of total and spectral solar irradiance (TSI and SSI) variability entitled EMPirical Irradiance REconstruction (EMPIRE). As with existing empirical models, TSI and SSI variability is given by the linear combination of solar activity indices. In empirical models, UV SSI variability is usually determined by fitting the rotational variability in activity indices to that in measurements. Such models have to date relied on ordinary least squares regression, which ignores the uncertainty in the activity indices. In an advance from earlier efforts, the uncertainty in the activity indices is accounted for in EMPIRE by the application of an error‐in‐variables regression scheme, making the resultant UV SSI variability more robust. The result is consistent with observations and unprecedentedly, with that from other modeling approaches, resolving the long‐standing controversy between existing empirical models and other types of models. We demonstrate that earlier empirical models, by neglecting the uncertainty in activity indices, underestimate UV SSI variability. The reconstruction of TSI and visible and IR SSI from EMPIRE is also shown to be consistent with observations. The EMPIRE reconstruction is of utility to climate studies as a more robust alternative to earlier empirical reconstructions.

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Reconstruction of solar irradiance variations in cycle 23: Is solar surface magnetism the cause?

Cited by 271 publications

References 16 publications

Solar forcing for CMIP6 (v3.2)

Solar forcing for CMIP6 (v3.2)

UV solar irradiance in observations and the NRLSSI and SATIRE‐S models

EMPIRE: A robust empirical reconstruction of solar irradiance variability

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