Low-frequency type II radio detections and coronagraph data to describe and forecast the propagation of 71 CMEs/shocks

TL;DR

This study analyzes 71 Earth-directed CMEs using radio and coronagraph data to develop improved methods for predicting shock arrival times at Earth, enhancing forecast accuracy by nearly 50%.

Contribution

It introduces two novel methods for tracking and predicting CME-driven shock propagation using type II radio emissions and coronagraph data.

Findings

The linear prediction method improves shock arrival forecasts by almost 50%.

Descriptive profiles of CME propagation provide insights into interplanetary travel.

Low-frequency radio emissions are effective indicators for CME shock tracking.

Abstract

The vulnerability of technology on which present society relies demands that a solar event, its time of arrival at Earth, and its degree of geoeffectiveness be promptly forecasted. Motivated by improving predictions of arrival times at Earth of shocks driven by coronal mass ejections (CMEs), we have analyzed 71 Earth-directed events in different stages of their propagation. The study is primarily based on approximated locations of interplanetary (IP) shocks derived from type II radio emissions detected by the Wind/WAVES experiment during 1997-2007. Distance-time diagrams resulting from the combination of white-light corona, IP type II radio, and in situ data lead to the formulation of descriptive profiles of each CME's journey toward Earth. Furthermore, two different methods to track and predict the location of CME-driven IP shocks are presented. The linear method, solely based on Wind/WAVES data, arises after key modifications to a pre-existing technique that linearly projects the drifting low-frequency type II emissions to 1 AU. This upgraded method improves forecasts of shock arrival time by almost 50%. The second predictive method is proposed on the basis of information derived from the descriptive profiles, and relies on a single CME height-time point and on low-frequency type II radio emissions to obtain an approximate value of the shock arrival time at Earth. In addition, we discuss results on CME-radio emission associations, characteristics of IP propagation, and the relative success of the forecasting methods.