Working Group 1 Report

Considerable research efforts have been made to detect and understand the variations in the entire spectral band and in the near-UV, visible and infrared spectral bands since the SOLERS22 1991. Workshop. Besides the ERB on NIMBUS7 and the ERBE experiments on ERBS, NOAA9 and NOAA1O satellites, additional space experiments provided data for total irradiance. The ACRIM 11 radiometer on board the Upper Atmospheric Research Satellite (UARS) has been measuring total solar i.rradiance since October 4, 1991. Two radiometers, SOVA1 and SOVA2, were placed on the European Retrievable Carrier (EURECA) satellite to monitor total SOIFir irradiance. The EURECA experiment was lunched on July 31, 1992 and it was retrieved on July 1, 1993. The SOVA experiment operated from August 10, 1992 until May 16, 1993. Irradiance observations were made simultaneously by the SOVA1 absolute radiometer CROM from the Royal Meteorological Institute of Belgium and by the SOVA2 absolute radiometer PM06 from PMOD/WRC at Davos, Switzerland. An ACR absolute radiometer from the Jet Propulsion Laboratory and SOLCON, a copy of SOVA1, operated together on the ATLAS1 and ATLAS2 space shuttle experiments. A summary of these space experiments is given in Fig. 1 (from Wi3.lson, 1993) .