Improvements of the shock arrival times at the Earth model STOA

TL;DR

This paper enhances the STOA shock arrival time model by refining transit time calculations and introducing new criteria based on solar activity and flare geometry, significantly improving prediction accuracy.

Contribution

The work presents a modified STOA model with improved transit time calculation and new prediction criteria incorporating sunspot numbers and flare angles.

Findings

Improved shock arrival time predictions, especially for non-shock flare events.

Reduced false alarms in shock predictions.

Enhanced model accuracy over the original STOA.

Abstract

Prediction of the shocks' arrival times (SATs) at the Earth is very important for space weather forecast. There is a well-known SAT model, STOA, which is widely used in the space weather forecast. However, the shock transit time from STOA model usually has a relative large error compared to the real measurements. In addition, STOA tends to yield too much `yes' prediction, which causes a large number of false alarms. Therefore, in this work, we work on the modification of STOA model. First, we give a new method to calculate the shock transit time by modifying the way to use the solar wind speed in STOA model. Second, we develop new criteria for deciding whether the shock will arrive at the Earth with the help of the sunspot numbers and the angle distances of the flare events. It is shown that our work can improve the SATs prediction significantly, especially the prediction of flare events without shocks arriving at the Earth.