Forcings in GISS Climate Model

Solar Irradiance

All spectral variations are derived from the NRLSSI models from Dr. Judith Lean ( Total solar irradiance (TSI) is derived from Wang et al. (2005). Extensions to the last millennium based on different calibrations can be found here. Extrapolations from the end of the series are based on an exactly repeating 11-yr copy of the previous cycle. Given the anomalous nature of SC24, this implies that CMIP5 simulations over-estimated the solar irradiance by a few tenths of W/m2 (Schmidt et al., 2014).

CMIP5 and More Recent Simulations

In CMIP5, TSI/SSI was based on Lean (2009) and Wang et al. (2005) (1850 to 2000) with extensions back to 850 CE based on reconstructions from Delaygue and Bard (as discussed in Schmidt et al., 2011).

More recently updates to TSI and spectral irradiance have been based on new calibration of the solar 'constant' to ~1361 W/m2 (Kopp and Lean, 2011). (Note this does not yet include updates for the recalibration of the group sunspot number (Clete et al., 2015)).

Line plot of total solar irradiance, 1850-2012

CMIP5 data available for download here (TXT file with 190 spectral bands, 850-2000).

Post-CMIP5 data available for download here (TXT file with 190 spectral bands, 1610-2014).

CMIP3 Simulations

This figure summarizes data used in 2004-2010 GISS GCM runs, based on Lean et al. (2002).


For further information about these data, please contact Dr. Judith Lean.


Clette, F., E. W. Cliver, L. Lefèvre, L. Svalgaard, and J. M. Vaquero, 2015: Revision of the Sunspot Number(s), Space Weather, 13, doi:10.1002/2015SW001264.

Delaygue, G. and E. Bard, 2011: An Antarctic view of Beryllium-10 and solar activity for the past millennium. Clim. Dyn., 36, 2201–2218, doi:10.1007/s00382-010-0795-1.

Kopp, G., and J. L. Lean, 2011: A new, lower value of total solar irradiance: Evidence and climate significance, Geophys. Res. Lett., 38, L01706, doi:10.1029/2010GL045777.

Lean, J., 2009: Calculations of Solar Irradiance (Document accessed 10/31/2015).

Lean, J., Y.-M. Wang, and N. R. Sheeley Jr., 2002: The effect of increasing solar activity on the Sun’s total and open magnetic flux during multiple cycles: Implications for solar forcing of climate, Geophys. Res. Lett., 29(24), 224, doi:10.1029/2002GL015880.

Schmidt, G. A., J. H. Jungclaus, C. M. Ammann, E. Bard, P. Braconnot, T. J. Crowley, G. Delaygue, F. Joos, N. A. Krivova, R. Muscheler, B. L. Otto-Bliesner, J. Pongratz, D. T. Shindell, S. K. Solanki, F. Steinhilber, and L. E. A. Vieira, 2011: Climate forcing reconstructions for use in PMIP simulations of the last millennium (v1.0). Geoscientific Model Development, 4, 33–45, doi:10.5194/gmd-4-33-2011.

Schmidt, G.A., D.T. Shindell, and K. Tsigaridis, 2014: Reconciling warming trends. Nature Geosci., 7, 158-160, doi:10.1038/ngeo2105.

Wang, Y.-M., J. L. Lean, and N. R. Sheeley Jr., 2005: Modeling the Sun’s magnetic field and irradiance since 1713, Astrophys. J., 625, 522– 538, doi:10.1086/429689.

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This page was written by Dr. Makiko Sato and Dr. Gavin Schmidt.

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