Decadal and Centennial Climate Response to SORCE SIM Observed Spectral Solar Forcing in GISS GCMAM

We examine the influence of the SORCE (Solar Radiation and Climate Experiment) SIM (Spectral Irradiance Monitor) observed spectral solar irradiance (SSI) variations on Earth's climate. We apply two spectral solar forcing scenarios, one SIM based, the other based on the SATIRE (Spectral And Total Irradiance REconstruction) model, as inputs to the GISS (Goddard Institute for Space Studies) GCMAM (Global Climate Middle Atmosphere Model) to study climate responses on decadal and centennial time scales. We find that the atmosphere has different temperature, ozone, and dynamic responses to the two solar forcing scenarios, even when the variations in TSI (Total Solar Irradiance) are the same. Solar variations under either scenario contribute a small fraction of the observed temperature increase since the industrial revolution. However multi decadal variation of the surface air temperature for the SIM-based solar forcing is much larger than its counterpart for SATIRE modeled solar forcing. Further research is required to investigate the mechanisms causing different responses, to examine TSI and SSI variations in the ascending phase of solar cycle 24, and to assess their implications for solar influence on climate.