Low-Frequency Type II Detections and Coronagraph Data to Describe and Forecast the Propagation of 71 CMEs/Shocks

H. CREMADES; O. C. ST. CYR; F. IGLESIAS; H. XIE; M. L. KAISER; N. GOPALSWAMY

San Francisco

Congreso; AGU Fall Meeting; 2015

American Geophysical Union

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 propagation. The study is primarily based on approximated locations of IP shocks derived from Type-II radio emissions detected by Wind/WAVES 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 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.