Space weather prediction tools based on low-frequency type II radio emissions

CREMADES, H.; IGLESIAS, F. A; O. C. ST. CYR

Cuzco

Conferencia; X COLAGE; 2014

Asociación Latinoamericana de Geofísica Espacial

P { margin-bottom: 0.08in; } Given the crucial consequences for Earth and its near-space activity, space weather forecasting has been a central subject of research in the past decades. This materializes nowadays in the rich and detailed data sets provided by multiple experiments specifically devoted to study the Sun-Earth connection. In this respect, coronal mass ejections (CMEs) constitute a key phenomenon, because their arrival to Earth and their associated MHD shocks are capable of triggering geomagnetic storms. Since it is infeasible to predict the occurrence of an Earth-directed CME, once it happened it is of vital importance to ascertain its time of arrival at Earth with the best possible accuracy. Radio emissions produced by shock waves ahead of CMEs allow their tracking in the interplanetary (IP) medium as they drift down in frequency when traveling away from the Sun, and thus serve as a tool to trace forward travel times to Earth. A database of Earth-directed events in different stages of their propagation from Sun to Earth is built, containing (i)CME height-time information from SOHO/LASCO coronagraph data, (ii) interplanetary (IP) shock approximate locations derived from low-frequency type II radio emissions detected by the Wind/WAVES experimentand, and (iii) in-situ shock time of arrival at the ACE and/or Wind spacecraft. Based on these, two different methods of tracking and predicting the location of IP shocks are tested, namely the linear extrapolation to 1 AU of type II radio emissions, and the second-order model of IP shock propagation. The latter arises from the combination of white-light corona, IP type II radio, and in-situ data, which is formulated on the basis of typical propagation profiles that represent each CME's journey toward Earth, together with important constrains on the main parameters. We discuss results on CME-radio emission associations, characteristics of IP propagation, and the success of the predictive models to forecast the arrival time of shocks at Earth. This synergistic study appears promising towards achieving better-educated forecasts of shock arrival time solely based on data from spacecraft located in the Sun-Earth line.