Solar Ultraviolet Spectral Irradiance: Early Results From the SOLar STellar Irradiance Comparison Experiment II Aboard the SORCE Spacecraft

Authors: William E. McClintock, Martin Snow, Gary J. Rottman, and Thomas N. Woods
Affiliation: LASP, University of Colorado

The SOLar STellar Irradiance Comparison Experiment II (SOLSTICE II) is a component of the Solar Radiation and Climate Experiment (SORCE) satellite that was launched in January 2003. SOLSTICE II uses a pair of diffraction grating spectrometers to measure solar irradiance from 115 nm to 320 nm with a spectral resolution of 0.1 nm at a cadence of 6 hours. Our goal is to provide a five-year ultraviolet solar irradiance record that has a 5% absolute accuracy and a 0.5% per year relative accuracy, which overlaps with measurements being made by SOLSTICE I, launched aboard the Upper Atmosphere Research Satellite (UARS) in September 1991. The SOLSTICE technique compares measurements of solar irradiance with those from an ensemble of bright, stable, main-sequence B-A stars. This allows us to accurately monitor changes in solar irradiance on the time scale of decades. It also provides a relative (rather than absolute) data set for future generations of researchers to use in solar irradiance variability studies.

We will present early results from SOLSTICE II and discuss its anticipated performance over the course of the SORCE mission.