Radio signatures of the origin and propagation of coronal mass ejections through the solar corona and interplanetary medium

Abstract

During a 16‐day period from February 5 to 20, 2000, a series of decametric‐to‐kilometric wavelength type II and type III radio events was observed by the WAVES radio experiment on board the Wind spacecraft. These radio events were related to observed coronal mass ejections (CMEs) and their associated flares. Each of the solar eruptive events was initiated by an intense, complex type III radio burst, which occurred within minutes of the liftoff on the CME. Some of the CMEs produced decametric‐hectometric (D‐H) type II radio emissions, which, when their frequency drift rates were sufficiently well defined, were used to provide a speed estimate. The complex type III and D‐H type II radio emissions gave an indication of the presence of a CME well before the CME was first observed in the coronagraph images. This series of CMEs also generated interplanetary (kilometric) type II radio emissions that tracked the CME‐associated shock through the interplanetary medium and established the terrestrial connection. Thus the various radio emissions associated with these solar eruptive events provided a global view of each entire Sun‐Earth connection event, from the initiation and liftoff of the CME at the Sun, to the propagation of the CME‐associated shock through the solar corona and interplanetary medium, to its arrival at 1 AU. Finally, we show that simultaneous Wind/Ulysses observations of the interplanetary type II radio emissions on February 9–10 provide important information on the nature of the type II emission, on the type II source locations, and on the radiation characteristics of the type II emissions. For example, these simultaneous observations clearly indicate that the sporadic nature of the type II radiation was intrinsic to the radio source region.