A practical database method for predicting arrivals of average'' interplanetary shocks at Earth

A practical database method for predicting the interplanetary shock arrival time at L1 point is presented here. First, a shock transit time database (hereinafter called Database-I) based on HAFv.1 (version 1 of the Hakamada-Akasofu-Fry model) is preliminarily established with hypothetical solar events. Then, on the basis of the prediction test results of 130 observed solar events during the period from February 1997 to August 2002, Database-I is modified to create a practical database method, named Database-II, organized on a multidimensional grid of source location, initial coronal shock speed, and the year of occurrence of the hypothetical solar event. The arrival time at L1 for any given solar event occurring in the 23rd solar cycle can be predicted by looking up in the grid of Database-II according to source location, the initial coronal shock speed, and the year of occurrence in cycle 23. Within the hit window of +/- 12 h, the success rate of the Database-II method for 130 solar events is 44%. This could be practically equivalent to the shock time of arrival (STOA) model, the interplanetary shock propagation model (ISPM), and the HAFv.2 model. To explore the capability of this method, it is tested on new data sets. These tests give reasonable results. In particular, this method's performance for a set of events in other cycles is as good as that of the STOA and ISPM models. This gives us confidence in its application to other cycles. From the viewpoint of long-term periodicity for solar activity, it is expected that the Database-II method can be applicable to the next solar cycle 24.