A tool to improve space weather forecasts: Kilometric radio emissions from Wind/WAVES

Abstract

For decades, space environment forecasters have used the appearance of metric Type II radio emission as a proxy for eruptions in the solar corona. The drift rate of these near‐Sun emissions is often turned into a speed, commonly assumed to be that of an MHD shock. However, their utility to forecast shock arrival times has not proved to be conclusive. Metric emissions can be detected by ground‐based antennae, while lower‐frequency components of these slowly drifting emissions can also be tracked by spacecraft in interplanetary space, as far down in frequency as that of the local plasma frequency. For a spacecraft at L1, this corresponds to about 25 kHz, or an electron density of about 7 cm−3 in the ambient solar wind. Here we report a recent study that aims to improve the predictions of shock arrival time at L1 by means of the low‐frequency emissions detected by WIND/WAVES. This technique, implemented on an extensive sample of hectometric and kilometric type II radio bursts, has yielded promising results.