Influence of the Initial Shock Speed Excited by Solar Flares on Shock Arrival Time Prediction

Abstract

AbstractBy using the Hakamada‐Akasofu‐Fry (HAF) solar wind model, we simulated 48 solar flare events during Carrington Rotation 1981 to 1985 and compared the simulated shock arrival time with observations by satellites at 1 AU. It is found that the initial solar wind shock speed deduced from the metric Type II radio burst observations plays an important role in the shock arrival time prediction. The match between predicted and observed shock arrival times (SATs) was considerably improved by iteratively adjusting the initial shock speed. We obtained the adjustment factors as the function of the initial shock speed for different hemispheres by using the statistical analysis and applied them to adjust the initial shock speed driven by the solar flares which occurred in the following five Carrington rotations (1986~1990), and the mean absolute error of the shock arrival time was reduced from 16 (15) hours to 12 (11) hours for the flare occurred on the western (eastern) hemisphere. This indicates that significant improvements can be made for the shock arrival time prediction by adjusting the initial shock speed using the statistical functions.