Comparison between the reconstructed TSI series (red circles for daily values and dashed ciel line for the 180-day running mean in the top part of each panel) and the PMOD TSI composite series (black circles for daily values and solid orange line for 180-day running mean values). At the bottom of each panel, the corresponding difference between the PMOD TSI and the reconstructed TSI (i.e. PMOD minus our reconstruction) is shown (black circles for daily values and orange line for the 180-day running mean). TSI series are reconstructed using the following data: RP Ca II K and RP blue (a); RP Ca II K and RP red (b); RPS Ca II K and RPS red (c); and SF Ca II K and RP red (d) observations. For all reconstructions, the PMOD TSI composite was used as the reference when deriving the regression coefficients.