The dynamics of the solar radio emission spectra is investigated for periods preceeding the proton flare at six wavelengths within a range from 3 cm up to 3 m. The spectrum shape is shown to be essentially dependent on the type of preburst changes. For the cases of powerful proton events the precursor spectra have two maxima within cm and dm ranges showing independent temporal evolution during the pre-flare period.Die Dynamik von solaren Radiospektren vor Protonenflares wird mit Hilfe von Beobachtungen auf sechs Wellenlangen im Bereich von 3 cm bis 3 m untersucht. Die Form des Spektrums hangt wesentlich vom Typ der Veranderungen in der Vorphase des Ausbruchs ab. Die Vorlaufer-Spektren groDer Protonenflares besitzen zwei Maxima im cm-bnv. dm-Bereich, die sich unabhangig voneinander zeitlich entwickeln.Key words: sun -atmosphere -radio emission spectra --flares AAA subject classification: 071It is actual to study pre-flare situations starting some tens of minutes before the flare onsets. Such investigations including those in the radio range open possibilities for the physical interpretation of pre-flare processes and for the determination of flare features and their diagnostics.With these aims, during the period of 1970 to 1986,46 hour and a half observational samples preceding the solar proton events were investigated. Data obtained at six wavelengths (3.2 cm, 10 cm, 30 cm, 46 cm, 1.5 and 3 m) at Zimenki station were used. The classification accepted for the description of radio emission bursts in Solar Geophysical Data has been used for identification of pre-burst situation. A study of absolute radio emission spectra dynamics preceding the proton eventsrelated bursts shows the essential dependence of the spectrum shape on the precursor type (with accepted classification).Figs. 1-3 illustrate examples of temporal evolution of the precursor spectra with different temporal variations of preburst radio emission. So, for slow radio emission intensity growth observed for all frequencies (RF type) the precursor spectrum is as a rule wide-band and close to flat one (see the dynamics of an event on 05.06. 79 starting at 0Sh06'" UT in Fig. 1 a, b). For precursors of the pulse type (S, 47 C, SF type) the precursor spectrum has a remarkable maximum in the cm range, which is conserved up to the beginning of the precursor burst. (Fig. 2a, b for the event of 11.08.72, starting from 1233" UT). Here the maximum of radiation is possible at different wavelengths for different precursors.The burst precursor dynamics related with the powerful proton flare of 14. 08. 79 with onset at lr42" UT is more complicated. As it can be seen from Fig. 3a, b the observation of the precursor dynamics reveals at least two spectrum features. The first of them related with the high-frequency edge of the spectrum growths continuously and has a sharp emission fall at 1 = 10 cm. The second one appears at I = 30 cm, further its maximum is shifted to 1 = 46 cm with nonmonotonous change of that component of the radiation.Probably, each of these features i...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.