The Impact of the Revised Sunspot Record on Solar Irradiance Reconstructions

Kopp, Greg; Krivova, N. A.; Wu, Chenguang; Lean, J.

doi:10.1007/s11207-016-0853-x

Cited by 78 publications

(67 citation statements)

References 51 publications

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“…Indeed, SSI models have not yet been thoroughly trained and tested with this new sunspot number. Recent results by Kopp et al (2016) suggest that this revision has little impact after 1885, and leads to greater solar-cycle fluctuations prior to that. Note that the NRLSSI version employed here uses the GSSN (Hoyt and Schatten, 1998), while SATIRE uses the annually averaged international sunspot number (v1.0).…”

Section: Proxies Usedmentioning

confidence: 99%

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: Proxies Usedmentioning

confidence: 99%

Solar forcing for CMIP6 (v3.2)

et al. 2017

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“…In the SILSO sunspot numbers (Clette et al, 2015), also shown in Figure 2a, eighteenth century solar cycles have notably larger amplitudes than in the Hoyt and Schatten (1998) group sunspot number; the SILSO sunspot number at the peak of solar cycle 19 is only 1.2 times larger than the peak of cycle 4. Kopp et al (2016) describe and compare the dependence of the NRLTSI2 and SATIRE reconstructions of TSI since 1610 on the adopted sunspot number record. Kopp et al (2016) describe and compare the dependence of the NRLTSI2 and SATIRE reconstructions of TSI since 1610 on the adopted sunspot number record.…”

Section: Sunspotsmentioning

confidence: 99%

“…For estimating solar irradiance between 1882 and the space era, the NRLTSI2 and NRLSSI2 models use direct observations of the areas and locations of sunspots made by the Royal Greenwich Observatory from 1882 to 1976 (Willis et al, 2013) to calculate a sunspot darkening function, which is scaled by 68% for cross calibration with that from the SOON observations (Coddington et al, 2016;Kopp et al, 2016). The facular index is a combination of Ca II K plage areas and the 10.7-cm solar radio flux after 1950 and sunspot numbers before then (Lean et al, 2001).…”

Section: The 1610-2016 Cementioning

confidence: 99%

“…Direct Be cosmogenic isotopes that the Paleoclimate Model Intercomparison Project recommends for use in simulations of preindustrial climate change (Jungclaus et al, 2017). SATIRE algorithmically transforms the sunspot number to estimates of the model's four separate inputs (dark sunspot umbra and penumbra and bright faculae and network; Kopp et al, 2016;Krivova et al, 2010). In (b) the average of the two sunspot number time series in (a) are compared with reconstructions of variations in total solar irradiance estimated from 10 Be (Steinhilber et al, 2009) and 14 C (Roth & Joos, 2013) cosmogenic isotopes.…”

Section: Introductionmentioning

confidence: 99%

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Estimating Solar Irradiance Since 850 CE

Lean

2018

Earth and Space Science

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Solar total and spectral irradiance are estimated from 850 to 1610 by regressing cosmogenic irradiance indices against the National Oceanic and Atmospheric Administration Solar Irradiance Climate Data Record after 1610. The new estimates differ from those recommended for use in the Paleoclimate Model Intercomparison Project (PMIP4) in the magnitude of multidecadal irradiance changes, spectral distribution of the changes, and amplitude and phasing of the 11‐year activity cycle. The new estimates suggest that total solar irradiance increased 0.036 ± 0.009% from the Maunder Minimum (1645–1715) to the Medieval Maximum (1100 to 1250), compared with 0.068% from the Maunder Minimum to the Modern Maximum (1950–2009). PMIP4's corresponding increases are 0.026% and 0.055%, respectively. Multidecadal irradiance changes in the new estimates are comparable in magnitude to the PMIP4 recommendations in the ultraviolet spectrum (100–400 nm) but somewhat larger at visible (400–700 nm) and near‐infrared (700–1,000 nm) wavelengths; the new estimates suggest increases from the Maunder Minimum to the Medieval Maximum of 0.17 ± 0.04%, 0.030 ± 0.008%, and 0.036 ± 0.009% in the ultraviolet, visible, and near‐infrared spectral regions, respectively, compared with PMIP4 increases of 0.17%, 0.021%, and 0.016%. The uncertainties are 1σ estimates accruing from the statistical procedures that reconstruct irradiance in the Medieval Maximum relative to the Modern Maximum, not from the specification of Modern Maximum irradiances per se. In the new estimates, solar irradiance cycle amplitudes in the Medieval Maximum are comparable to those in the Modern Maximum, whereas in the PMIP4 reconstruction they are at times almost a factor of 2 larger at some wavelengths and differ also in phase.

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“…The most critical implication of these series is that they yield different long-term trends for the activity of the Sun ; Kopp et al 2016). Over the 19th and 20th centuries, ClLi16 and SvSc16 show no trend, while HoSc98 and UEA16 show an increase in solar activity.…”

Section: Introductionmentioning

confidence: 99%

New reconstruction of the sunspot group numbers since 1739 using direct calibration and “backbone” methods

Chatzistergos

Usoskin

Kovaltsov

et al. 2017

A&A

113

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Context. The group sunspot number (GSN) series constitute the longest instrumental astronomical database providing information on solar activity. This database is a compilation of observations by many individual observers, and their inter-calibration has usually been performed using linear rescaling. There are multiple published series that show different long-term trends for solar activity. Aims. We aim at producing a GSN series, with a non-linear non-parametric calibration. The only underlying assumptions are that the differences between the various series are due to different acuity thresholds of the observers, and that the threshold of each observer remains constant throughout the observing period. Methods. We used a daisy chain process with backbone (BB) observers and calibrated all overlapping observers to them. We performed the calibration of each individual observer with a probability distribution function (PDF) matrix constructed considering all daily values for the overlapping period with the BB. The calibration of the BBs was carried out in a similar manner. The final series was constructed by merging different BB series. We modelled the propagation of errors straightforwardly with Monte Carlo simulations. A potential bias due to the selection of BBs was investigated and the effect was shown to lie within the 1σ interval of the produced series. The exact selection of the reference period was shown to have a rather small effect on our calibration as well. Results. The final series extends back to 1739 and includes data from 314 observers. This series suggests moderate activity during the 18th and 19th century, which is significantly lower than the high level of solar activity predicted by other recent reconstructions applying linear regressions. Conclusions. The new series provides a robust reconstruction, based on modern and non-parametric methods, of sunspot group numbers since 1739, and it confirms the existence of the modern grand maximum of solar activity in the second half of the 20th century.

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The Impact of the Revised Sunspot Record on Solar Irradiance Reconstructions

Cited by 78 publications

References 51 publications

Solar forcing for CMIP6 (v3.2)

Solar forcing for CMIP6 (v3.2)

Estimating Solar Irradiance Since 850 CE

New reconstruction of the sunspot group numbers since 1739 using direct calibration and “backbone” methods

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