Data

SATIRE (Spectral And Total Irradiance REconstructions) is a semi-empirical model. It assumes that all irradiance changes on time scales longer than one day are caused by changes in the surface magnetic field. The solar surface magnetic field manifests itself in form of various brightness structures, such as dark sunspots and pores or bright faculae and the network. SATIRE has two ingredients. The first one is the fractional coverage and the distribution of various brightness structures on the solar visible disc. They are derived from solar observations and vary with time. The second component describes the brightness of various structures or their contrast with respect to the surrounding "quiet Sun" surface. These contrasts depend on the position of the feature on the solar disc and on the wavelength. They are independent of time and have been calculated from the corresponding semi-empirical model atmospheres (i.e. models describing the structure of the solar atmosphere). Depending on the observational data we use to describe the surface distribution of the magnetic structures, different versions of SATIRE have been developed. The SATIRE data sets and ancillary data sets developed along the model are organized here by the time period they cover; the modern-era, telescope-era and holocene.

Modern-Era

SATIRE-S (since 1974)

SATIRE-S uses full-disc magnetograms and continuum images of the Sun to quantify the fractional disc area coverage by different surface components (quiet Sun, sunspot umbrae, sunspot penumbrae, faculae and network) as well as their spatial distribution. The most recent version of the model uses the magnetograms from NSO KP (1974-1999), Mt Wilson (1983-2013), SoHO/MDI (1999-2009) and SDO/HMI (since 2010), as well as unsigned magnetograms reconstructed from Ca II K observations from Meudon (1974-2017), San Fernando (1992-2013), and Rome (2000-2023) and is described in detail in Chatzistergos et al. (2025, A&A. doi:10.1051/0004-6361/202554044). Updates on weekly basis.

TSI (ASCII format)

SSI (ASCII format)

TSI and SSI (IDL format)

Description

Facular brightening and spot darkening separately

Previous version by Yeo et al. (2014, A&A 570, A85) using only the magnetograms from NSO KP (1974-1999), SoHO/MDI (1999-2009) and SDO/HMI (since 2010). Updates on request.

Earlier versions available on request:
UV irradiance (115-400 nm; 1.1.1974-31.12.2007) from Krivova et al. (2009, JGR doi:10.1029/2009JD012375).
SSI (115-160000 nm; 1974-2009) from Ball et al. (2014, Journal of Atmospheric Sciences, 71, 4086-4101).

EMPIRE

Alternative reconstruction of TSI and SSI based on what is termed the proxy approach. Solar irradiance variability is given by the linear combination of facular and sunspot indices, the coefficients of which is determined by their regression to measured solar irradiance. It has been demonstrated that earlier proxy models underestimate UV SSI variability as a result of them ignoring the uncertainty in the index data in the regression by applying ordinary least squares (Yeo et al. 2017, JGR doi:10.1002/2016JA023733). EMPIRE, by applying a regression scheme that takes the uncertainty in the index data into account, produces UV SSI variability consistent with SATIRE and measurements.

Daily TSI (since 1947)

Daily SSI (since 1947)

SATIRE-3D

The first model of solar irradiance variability to, by incorporating state-of-the-art 3D MHD numerical simulations of the solar surface and atmosphere, not require any calibration to measured variability (Yeo et al. 2020, GRL doi:10.1029/2020GL090243). (Other models, without exception, contain free parameters constrained by comparing the model output to solar irradiance observations.)

Daily TSI (2010-2023)

Empirical TSI model based on photometric sum approach

Alternative reconstruction of TSI based on the photometric sum approach (Chatzistergos et al. 2020, J. Space Weather. Space Clim. doi:10.1051/swsc/2020047). Total solar irradiance is reconstructed with a linear regression of the photometric sum series to the PMOD TSI composite series. The photometric sum series are computed from full disc Rome/PSPT observations in the Ca II K line and a blue/red continuum interval.

Daily TSI (1996-2022)

Telescope-Era

SATIRE-T

SATIRE-T takes the sunspot number (1610-1876) and total sunspot area (since 1876) into a simple physical model that describes the evolution of the solar surface magnetic field. From the model output, we derive the fraction of the solar disc covered by each magnetic component as a function of time, which is then used to reconstruct total (TSI) and spectral (SSI) solar irradiance back to the Maunder minimum: Wu et al. (2018, A&A doi:10.1051/0004-6361/201832956)

SATIRE-T2

SATIRE-T2 is an alternate version of SATIRE-T that employs a surface flux transport model (SFTM) to describe the evolution of the solar surface magnetic field (instead of the simpler model used by SATIRE-T). The input to the SFTM is still the sunspot number and total sunspot area. The model is presented by Dasi-Espuig et al. ( 2014, A&A 570, A23 and 2016, A&A 590, A63).

SATIRE-T (1610-1974) + SATIRE-S (since 1974)

This data set is a combination of SATIRE-T before 23 August 1974 (Krivova et al. 2010, JGR doi:10.1029/2010JA015431) and SATIRE-S afterwards (Yeo et al. 2014, A&A 570, A85)

Daily TSI (since 1610)
Daily SSI (since 1610)
Daily TSI (since 1850) This is same as "daily TSI (since 1610)" except truncated at 1850
Daily SSI (since 1850) Again, same as "daily SSI (since 1610)" except truncated at 1850

Annually mean TSI (1700-2012) This is an earlier composite based on an earlier version SATIRE-T (Krivova et al. 2010, JGR doi:10.1029/2010JA015431) before 1974 and SATIRE-S (1974-2010: Ball et al. 2012, A&A 541, A27; 2011-2012: Yeo et al. 2014, A&A 570, A85) afterwards. It has been used for Table 8.SM.4 of the IPCC5 WG1 Report (Chapter 8, Supplementary Material).

Sunspot area and PSI

Composite of sunspot group area, daily total sunspot area and PSI calculated after cross-calibration of measurements by different observers: Mandal et al. (2020, A&A doi:10.1051/0004-6361/202037547)

Solar 10.7 cm flux (F10.7)

Reconstruction of the F10.7 from the daily total sunspot area: Yeo et al. (2020, A&A doi:10.1051/0004-6361/202037739)

Daily F10.7 (since 1874)

Sunspot group number

Composite of the sunspot group number after cross-calibration of measurements by different observers: (Chatzistergos et al. 2017, A&A doi:10.1051/0004-6361/201630045)

Daily sunspot group number (since 1739)

Monthly sunspot group number (since 1739)

Annual sunspot group number (since 1739)

Plage Area (since 1892)

Composite of plage area in the Ca II K line calculated after cross-calibration of Ca II K spectroheliograms and filtergrams from 38 observatories: Chatzistergos et al. (2020, A&A doi:10.1051/0004-6361/202037746 and 2023, JSWSC doi:10.1051/swsc/2024006)

Daily plage area (since 1892)

Monthly plage area (since 1892)

Annual plage area (since 1892)

Holocene

SATIRE-M

SATIRE-M is similar to SATIRE-T, except instead of using the observed sunspot number, which only goes back to the Maunder Minimum, it uses the reconstruction of the sunspot number over the Holocene by Wu et al. (2018, A&A doi:10.1051/0004-6361/201731892) as input. The model is used to reconstruct decadal total (TSI) and spectral (SSI) solar irradiance over the last 9000 years: Wu et al. (2018, A&A doi:10.1051/0004-6361/201832956)

Solar Modulation Potential and Sunspot Number

14C and 10Be are produced in the terrestrial atmosphere through interactions with the galactic cosmic ray, which is modulated by solar activity. It is therefore possible to link, through physical models, the concentration of 14C and 10Be to the evolution of the solar surface magnetic field. Taking this approach, we derived the solar modulation potential over the Holocene, and the corresponding reconstruction of the sunspot number from the 14C and 10Be records: Wu et al. (2018, A&A doi:10.1051/0004-6361/201731892) .

Decadal solar modulation potential (since 6755 BCE)

Decadal sunspot number (since 6755 BCE)

Paleoclimate Modelling Intercomparison Project - Phase 4

A composite of SATIRE-H, derived as above but using the 14C and 10Be records seperately, SATIRE-T (1610-1974) and SATIRE-S (1974-2015) provides the solar forcing input for the Paleoclimate Modelling Intercomparison Project - Phase 4 or PMIP4 (Jungclaus et al. 2016, Geosci. Model Dev. Discuss. doi:10.5194/gmd-2016-278).

There is an alternate version of the above data sets (14C-based, 10Be-based), where the 1850-2015 segment is given by the SSI data set of the Coupled Model Intercomparison Project - Phase 6 or CMIP6 ( Mathes et al. 2017, Geosci. Model Dev. Discuss. doi:10.5194/gmd-10-2247-2017), which is an amalgamation of the SATIRE-T, SATIRE-S and NRL models.