Total solar irradiance variability - 5 years of ERBE data

Data obtained by the ERBS solar monitors measuring total solar irradiance variability are discussed. The ERBS and NOAA-99 monitors derived 1365 W/sq m as the magnitude of the solar irradiance, normalized to 1 astronomical unit. The NOAA-10 monitor yielded 1363 W/m as the magnitude of the irradiance. The long-term precision of the monitors was demonstrated by the detection of the decreasing and increasing trends in the irradiance at levels of the order of 0.03 to 0.05 percent per year. The ERBS and NOAA-9 measurements demonstrated that solar variability exists in a systematic mode which is directly correlated with the solar magnetic activity, indicated by sunspot activity. It is argued that during the decline of sunspot cycle 22, the solar irradiance variability may be entirely different from that which was observed during the decline of cycle 21.