Abstract A rare Type I-like noise storm was observed with the solar radio spectrometers (1.0–2.0 GHz and 2.60–3.8 GHz) at National Astronomical Observatories of China (NAOC) on September 23, 1998. We concentrate on checking the Type I-like noise storm occurred in the decay phase of a Type IV radio burst. This noise storm consists of many Type I bursts and isolated Type III or Type III pair bursts. It has a bandwidth of ≤0.5 GHz. The duration of each Type I burst is of the order of 100–300 ms. The total duration is greater than 11 minutes. The circular polarization degree of the components of Type I and associated Type III bursts are about 40%–100% and almost 100%, respectively, which is greater than that of the background continuum (nearly the precision of our instrument). This short decimetric Type I-like storm may be another kind or the extension of the kind of metric Type I storm, and may possess the duality of metric and decimetric radio emission. It may be in favor of an earlier emission mechanism of the fundamental plasma radiation due to the coalescence of Langmuir waves with low-frequency waves.
Keywords Sun --- radio radiation --- Type I noise storm
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