J/A+A/713/A135ivo://CDS.VizieR/J/A+A/713/A135CDSChatzistergos T.Krivova N.A.Owens M.Egorova T.2026-09-11T06:57:31Z2026-09-11T07:57:04ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frthe-sunastronomical-modelsmagnetic-fieldsConstraining long-term variations in total solar irradiance (TSI) is important for assessing the solar influence on Earth's climate. Most current irradiance reconstructions suggest only a modest secular increase in TSI between the 1700 and 1986 activity minima (<1Wm-2), while two models suggest substantially larger changes of 2.1-5.9W/m^2^. These are the Code for the High spectral ResolutiOn recoNstructiOn of Solar irradiance (CHRONOS) and the model by Penza et al. (2024ApJ...976...11P; PEA24, hereafter). Although the two models differ substantially in their architecture, both use cosmogenic isotope records combined with neutron monitor data to describe the long-term irradiance variability. However, cross-calibrating modulation potential reconstructions from cosmogenic isotopes against neutron monitor data remains highly uncertain. We reassess the origin and the magnitude of the large secular trends in the CHRONOS and PEA24 models. We update the CHRONOS and PEA24 models using recent heliospheric modulation potential and open solar flux reconstructions based on geomagnetic data and neutron monitor measurements, which provide a more reliable connection between cosmogenic isotope and neutron monitor records. We further apply a more robust smoothing methodology for the long-term series. These allow the secular component of the reconstructions to be extended consistently to the satellite era and compare the resulting TSI reconstructions with direct TSI measurements. We find that the original CHRONOS and PEA24 reconstructions substantially overestimated the secular variability in irradiance. When constrained by direct TSI measurements, CHRONOS yields a TSI increase of about 0.1+/-0.17W/m^2^ between the 1700 and 1986 minima, while PEA24 returns about 0.2-0.25 W/m^2^. Our analysis indicates that the previously inferred large secular trends arose primarily from improper linking cosmogenic isotope and neutron monitor records, together with issues in the adopted smoothing approach. The updated reconstructions presented here point toward a relatively modest secular increase in TSI since the Maunder Minimum, likely below 1 Wm-2, consistent with the majority of current irradiance models.2026A&A...713A.135Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/713/A135CatalogResearchIsServedByTAP VizieR generic servicerelated-toVI/152 : SOVAP-PICARD total solar irradiance (Meftah+, 2016)J/ApJ/920/100 : Reconstruction of solar irradiance from 1700 to 2019https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/713/A135https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/713/A135http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/713/A135https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/713/A135https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/713/A135http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/713/A135GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/713/A135/chronosAnnual total solar irradiance (TSI) reconstructions with the CHRONOS modelrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintYearYearyrtimedoubleTSI1CHRONOS TSI reconstruction with SSR11+OW24+US17 modulation potentialphot.flux.boldoubleTSI2CHRONOS TSI reconstruction with US16+OW24+US17 modulation potentialphot.flux.boldoubleTSI3CHRONOS TSI reconstruction with MU16+OW24+US17 modulation potentialphot.flux.boldoubleTSI4CHRONOS TSI reconstruction with MC17+OW24+US17 modulation potentialphot.flux.boldoubleJ/A+A/713/A135/pea24Annual total solar irradiance (TSI) reconstructions with the Penza modelrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintYearYearyrtimedoubleTSIPEA24 TSI reconstruction with OSF2phot.flux.boldouble