A new SATIRE-S spectral solar irradiance reconstruction for solar cycles 21-23 and its implications for stratospheric ozone

The authors present a revised and extended total and spectral solar irradiance (SSI) reconstruction, which includes a wavelength-dependent uncertainty estimate, spanning the last three solar cycles using the Spectral and Total Irradiance Reconstruction-Satellite era (SATIRE-S) model. The SSI reconstruction covers wavelengths between 115 and 160 000nm and all dates between August 1974 and October 2009. This represents the first fullwavelength SATIRE-S reconstruction to cover the last three solar cycles without data gaps and with an uncertainty estimate. SATIRE-S is compared with the Naval Research Laboratory Spectral Solar Irradiance (NRLSSI)model and ultraviolet (UV) observations from the Solar Radiation and Climate Experiment (SORCE) Solar Stellar Irradiance Comparison Experiment (SOLSTICE). SATIRE-S displays similar cycle behavior to NRLSSI for wavelengths below 242nm and almost twice the variability between 242 and 310nm. During the decline of the last solar cycle, between 2003 and 2008, the SSI from SORCE SOLSTICE versions 12 and 10 typically displays more than 3 times the variability of SATIRE-S between 200 and 300 nm.All three datasets are used to model changes in stratospheric ozone within a 2D atmospheric model for a decline from high solar activity to solar minimum. The different flux changes result in different modeled ozone trends. Using NRLSSI leads to a decline in mesospheric ozone, while SATIRE-S and SORCE SOLSTICE result in an increase. Recent publications have highlighted increases in mesospheric ozone when considering version 10 SORCE SOLSTICE irradiances. The recalibrated SORCE SOLSTICE version 12 irradiances result in a much smaller mesospheric ozone response than that of version 10, and this smaller mesospheric ozone response is similar in magnitude to that of SATIRE-S. This shows that current knowledge of variations in spectral irradiance is not sufficient towarrant robust conclusions concerning the impact of solar variability on the atmosphere and climate.