Reviews of long-term predictions of solar cycles have shown that a precise prediction with a lead time of 2 years or more of a solar cycle remains an unsolved problem. We used a simple method, the method of similar cycles, to make long-term predictions of not only the maximum amplitude but also the smoothed monthly mean sunspot number for every month of Solar Cycle 23. We verify and compare our prediction with the latest available observational results.
The electron pulsation event is defined in the paper. Firstly, a slow Halo CME on March 16, 2001 that led to low-energetic solar proton event, electron pulsation event and major geomag- netic storm was analyzed. And then, dozens of events are collected. The interrelations among the solar flare, CME, solar proton event, electron pulsation event and geomagnetic storm are studied. The results show that: (i) Solar proton events can be regarded as the indication that CMEs get to the earth and the electron pulsation events can be regarded as the indication of solar proton flux. (ii) Not only can fast CMEs strongly influence the earth, but also slow CMEs can influence the earth, and its influences are more frequent and cannot be neglected. (iii) Most of high-energetic solar proton events with E≥10 MeV can lead to geomagnetic storms, but most of the medium and weak geomagnetic storms result from low-energetic solar proton events that are caused by CMEs. (iv) Both the electron pulsation events and geomagnetic storms are the link effects of high-and low-energetic solar proton events, but the occurrence of electron pulsation event are generally prior to the geomagnetic storm. So in the circumstance where the near real-time observing data of the low-energetic solar proton event cannot be obtained, we can regard electron pulsation event as the indication of the low-energetic solar proton flux reaching the earth, which can be used as one of the important references of short-term prediction and alert of the geomagnetic storm.
In this note, we define firstly a compositive parameter as an index describing the level of solar activity in a solar cycle. The parameter is derived from a combination of the smoothed monthly mean sunspot number with the fluctuation of the associated monthly mean sunspot numbers to the smoothed one. Then, a method is developed for estimating the time of the appearance of a solar maximum based on the conception of similar cycles. An application ofthe method to the 23rd solar cycle shows that the maximum of the cycle should have appeared in the period from April to August 2000, and the descending phase of Cycle 23 has come.
WANG JialongGONG JiancunTONG JizhouSUN JinglanZHU Cuilan
