SOHO/VIRGO total solar and spectral irradiance variations

The Variability IRradiance Gravity Oscillation (VIRGO) experiment on SOHO has been observing total solar and spectral irradiances at 402, 500, and 862 nm since January 1996. The VIRGO observations have shown that solar active regions influence both total and spectral irradiances, although the amplitude of the variations seems to be the largest in near-UV and visible irradiances. In this paper we compare the VIRGO irradiance data with the Photometric Sunspot Index (PSI) and the Mg II h & k core-to-wing ratio, derived from the UARS/SUSIM UV irradiance observations at the 280 nm line. We also show a useful method to eliminate the instrumental trends from the VIRGO spectral irradiances.