Predictions of interplanetary shock arrivals at Earth: Dependence of forecast outcome on the input parameters

Predictions of interplanetary shock arrivals at Earth are important to space weather because they are often followed by geomagnetic disturbances that disrupt human technologies. The success of numerical simulation predictions depends on the codes and on the inputs obtained from solar observations. The inputs are usually divided into the more slowly varying background solar wind, onto which short‐duration solar transient events are superposed. This paper examines the dependence of the prediction success on the range of values of the solar transient inputs. These input parameters are common to many 3‐D MHD codes. The predictions of the Hakamada‐Akasofu‐Fry version 2 (HAFv2) model were used because its predictions of shock arrivals were tested, informally in the operational environment, from 1997 to 2006. The events list and HAFv2's performance were published in a series of three papers. The third event set is used to investigate the success and accuracy of the predictions in terms of the input parameter ranges (considered individually). By defining three thresholds for the input speed, duration, and X‐ray class, it is possible to categorize the prediction outcomes by these input ranges. The X‐ray class gives the most successful classification. Above the highest threshold, 89% of the predictions were successful while below the lowest threshold, only 40% were successful. The accuracy, measured in terms of the time differences between the observed and predicted shock arrivals, also shows largest improvement for the X‐ray class. Guidelines are presented for space weather forecasters using the HAFv2 or other interplanetary simulation models.