Performance of interplanetary shock prediction models: STOA and ISPM

The shock time of arrival (STOA) model and the interplanetary shock propaga tion model (ISPM) give predictions of the time of arrival and strength of s olar-initiated interplanetary shocks. This paper presents the first operati onal predictions made of interplanetary shocks that follow solar events. Th e time interval of this study was February 1997-March 1999 (the rise of Sol ar Cycle 23). The results are presented in contingency-table form (whether or not a shock was predicted and/or observed) and also as the time differen ces (errors) between the predicted and observed shock arrivals. These resul ts are compared to the accuracies that would be obtained using a constant, representative value (Rule of Thumb or R-T) for the transit time. The resul ts show the percentage of successful predictions to within an accuracy of 1 2 h of shocks for the STOA, ISPM and R-T are 53, 58, and 33%, respectively. The corresponding root mean square (rms) errors of the shock arrival times are 15.0, 15.1 and 14.8 h. Note that the rms heavily weights outlying poin ts, so although only 3 of the ISPM-predictions were off by more than 12 h, the ISPM rms is worse than that for STOA and R-T models; both of which had prediction errors > \12\ h for eight events. Statistics presented in this p aper not only show the capabilities of these models, but also allow for com parison to future shuck-arrival forecasting models. These results may be co nsidered as reference metrics in evaluating forecasting skill. The relation ship of the interplanetary shocks to geomagnetic activity is also briefly c onsidered. Published by Elsevier Science Ltd.