Using soft X-ray observations to help the prediction of flare related interplanetary shocks arrival times at the Earth

It is very important to predict the shock arrival times (SATs) at Earth for space weather practice. In this paper we use the energy of soft X-ray during solar flare events to help predict the SATs at Earth. We combine the soft X-ray energy and SAT prediction models previously developed by researchers to obtain two new methods. By testing the methods with the total of 585 solar flare events following the generation of a metric type II radio burst during the Solar Cycle 23 from September 1997 to December 2006, we find that the predictions of SATs at Earth could be improved by significantly increasing POD_n, the proportion of events without shock detection that were correctly forecast. POD_n represents a method's ability in forecasting the solar flare events without shocks arriving at the Earth, which is important for operational predictions.