Solar radio spectrum extended to 10 km wavelength

KNOWLEDGE of the range of solar radio burst flux densities is important for understanding the physical processes generating these bursts. However, past summaries of the solar radio spectrum 1,2 , compiled from ground-based observations, have not extended to wavelengths much below 10m because the ionosphere of the Earth is opaque to longer wavelengths. Consequently, radio waves generated at altitudes above 5–10 solar radii in the outer corona can be observed only from above the ionosphere. The spectrum presented here covers wavelengths of 1mm to 10km; the observations between wavelengths of 100 m and 10 km were made by Earth satellites.