Fair space weather for solar cycle 24

[1] We discuss the polar field precursor method of solar activity forecasting, first developed 3 decades ago. Using this method the peak amplitude of the next solar cycle (24) is estimated at 124 ± 30 in terms of smoothed F10.7 Radio Flux and 80 ± 30 in terms of smoothed international or Zurich Sunspot number (Ri or Rz). This may be regarded as a ‘‘fair space weather’’ long term forecast. To support this prediction, direct measurements are obtained from the Wilcox and Mount Wilson Solar Observatories. Additionally, coronal features do not show the characteristics of well-formed polar coronal holes associated with typical solar minima, but rather resemble stunted polar field levels. The question is raised: why have the Sun’s polar fields not strengthened comparably in the 2000–2005 time period, as in the previous few decades? The dramatic field changes seen suggest the importance of field motions associated with photospheric (e.g. meridional) flows for the Sun’s dynamo. Flows may also play a role in active region development, e.g., it is possible that field magnification occurs through surface processes, namely active region field strengthening (sunspot growth) through the influx of like photospheric magnetic regions, and even the influx of ERs (ephemeral regions), wherein the same sign (like) flux could be differentially drawn into spots of that sign, leading to field growth. Citation: Schatten, K. (2005), Fair space weather for solar cycle 24, Geophys. Res. Lett., 32, L21106, doi:10.1029/ 2005GL024363.