A study of the spectrum and the polarization of the noise storm continua between 234 and 40 MHz |
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| Authors: | A Böhme |
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| Institution: | (1) Zentralinstitut für Astrophysik, AdW der DDR, Observatorium für solare Radioastronomie, 1501 Tremsdorf, G.D.R. |
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| Abstract: | Intense noise storm continua at low frequencies are mostly observed in the later phase of solar cycles (Böhme, 1989). Radioheliographs may be needed to determine whether this effect is mainly caused by type I or type III continua. However, based on single-frequency records from the Tremsdorf Observatory a method to discriminate type I and type III continua even from polarization measurements was derived. Intense 40 MHz continua identified by spectral criteria as a type III continuum are more weakly polarized than type I continua. The increase in the number of intense continua at frequencies  64 MHz during the second, compared to the first, activity maximum of cycle No. 20 was due to an enhanced number of continua with a significant contribution of type I continuum. Relations between the parameters of the continua and the concurrent storm bursts confirm the validity of the above-mentioned ideas and may be useful to test models which try to explain the generation of type I and type III storms under common aspects. |
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