Statistical Survey of Type III Radio Bursts at Long Wavelengths Observed by the Solar TErrestrial RElations Observatory (STEREO)/Waves Instruments: Goniopolarimetric Properties and Radio Source Locations
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We have performed a statistical analysis of a large number of Type III radio bursts observed by STEREO between May 2007 and February 2013. Only intense, simple, and isolated cases have been included in our data set. We focused on the goniopolarimetric (GP, also referred to as direction-finding) properties at frequencies between 125 kHz and 2 MHz. The apparent source size γ is very extended (≈ 60∘) for the lowest analyzed frequencies. Observed apparent source sizes γ expand linearly with a radial distance from the Sun at frequencies below 1 MHz. We show that Type III radio bursts statistically propagate in the ecliptic plane. The calculated positions of radio sources indicate that scattering of the primary beam pattern plays an important role in the propagation of Type III radio bursts in the interplanetary medium.
KeywordsPlasma radiation Solar radio emissions
The authors would like to thank the many individuals and institutions who contributed to making STEREO/Waves possible. O. Kruparova acknowledges the support of the Czech Grant Agency grant GP13-37174P. O. Santolik acknowledges the support of the Czech Grant Agency grant GAP205/10/2279. V. Krupar thanks for the support of the Czech Grant Agency grant GAP209/12/2394.
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