1 Introduction The 47 years space record of total solar irradiance (TSI) began in 1978 and is, for the most part, an uninterrupted record of partially overlapping measurements from individual instruments that contain offsets in magnitude that reflect differences in the calibration scale of the individual instruments. TSI is an energy source at the top of Earth's atmosphere that is more than 3000x larger than all other external energy sources combined (Kren et al., 2017).
