Evaluations of Sun-Earth Radiative Connection Over Solar Cycle 23

The Solar Radiation Physical Modeling tools produced Solar Spectral Irradiance (SSI) reconstruction that covers the past solar cycle (SC23) from 1997 to 2009. This reconstruction uses the spectral synthesis for the range 0.2 nm to 100 micron at very good spectral resolution, and the images of the solar disk obtained by the Rom/PSPT (2001-2009) and the Meudon observatory (1997-2001) instruments. The resulting SSI matches fairly well the SORCE observations during the decay of the cycle (2004-2009), including the opposite phase of the near-UV and visible spectrum variations. The reconstruction is now being used to evaluate the effects of SSI variations, and the effects of Total Solar Irradiance (TSI) variations, on the Earth's atmosphere over an entire solar cycle. A preliminary step was to use the MODTRAN@ atmospheric radiative transfer code for evaluating solar heating rates at various solar conditions and latitudes, but with a fixed composition and no feedbacks. In another step we evaluated the changes to photolysis rates and find fairly significant effects in the stratosphere, smaller effects in the troposphere, and of course important effects in the mesosphere and above. Now with Whole Atmosphere Community Climate Model (WACCM) we are starting to examine the full effects of the SSI and TSI variations on the complete atmosphere by including full chemistry and dynamics. This presentation will show the results obtained in these studies.