Total solar irradiance variations

Abstract

Total solar irradiance has been monitored from space for nearly two decades. These space-borne observations have established conclusively that total solar irradiance changes over a wide range of periodicities-from minutes to the 11-year solar cycle. Since the total energy flux of the Sun is the principal driver for all Earths atmospheric phenomena, the accurate knowledge of the solar radiation received by the Earth and its variations is an extremely important issue. In this paper we review the long-term variations of total solar irradiance during solar cycles 21 and 22. We conclude that, within the current accuracy and precision of the measurements, the minimum level of total solar irradiance is about the same for both solar cycles 21 and 22.