A Remarkably Accurate Predictor of Sunspot Cycle Amplitude

The area ratios of sunspots to white light faculae in the first two years of sunspot cycles 12-21 correlate remarkably well with the peak amplitudes of those cycles between 1878-1980 (Brown and Evans, 1980). This finding could not be used to predict subsequent cycle amplitudes because the Royal Greenwich Observatory program of facular area measurements was discontinued in 1976. We use continuum images from the Michelson Doppler Imager (MDI) and the Heliospheric and Magnetic Imager (HMI) to show that the close relation holds also for cycle 24, and we predict an amplitude of approximately 185 for the current cycle 25.