A brief review on the presentation of cycle 24, the first integrated solar cycle in the new millennium
Abstract. The status of the extended solar activity minimum, since the second half of 2007, has been briefly instructed to the solar-terrestrial community. Cycle 24 has the most spotless days since cycle 16, and probably even since the modern cycles, latitudes of high-latitude (>35°) sunspots belonging to a new cycle around the minimum time of the cycle are statistically the lowest at present, compared with those of cycle 12 onwards, and there is only one or no sunspots in a month appearing at high latitudes (>20°) for 58 months (from November 2003 to September 2008), which is observed for the first time since cycle 12 onwards. The solar wind velocity and pressure, 10.7 cm solar radio flux, the polar solar magnetic field, solar total irradiance, and so on reach their minima during the 23–24 cycle minimum time. In order to explain the present extreme low activity, we introduced here one possible mechanism using helio-seismology observations. Viewing, from the long-term running of the time scales of both the Gleissberg period and millenniums, the extended solar activity minimum becomes logical. According to the present observations, the cycle 24 should start in November 2008. Solar activity is predicted at being about 30% lower in cycle 24 than in cycle 23, synthesizing the typical predictions of solar activity, including those given by NASA and NOAA. The 24th solar cycle is sluggishly coming and it should be an opportune moment for studying solar physics and solar-terrestrial physics.