Title: Spectral/time characteristics of radio precursors of solar flares
Author: O.A.Sheiner
Affil: Radiophysical Research Institute
Email: rfj@nirfi.sci-nnov.ru
Authors: M.S.Durasova, T.S.Podstrigatch, and V.M.Fridman
Affils: Radiophysical Research Institute
Abstract: We have worked out a spectral approach for studying the preburst situations, which characterises the activity development at large scales of the solar atmosphere altitudes and, therefore, allows us to obtain more detailed information on the dynamics of activity development.
Observations of fluxes of solar radio emission and their time features, which were conducted at ``Zimenki'' facility (NIRFI, Russia) during 1967-1992, including the data for six discrete frequencies (9100MHz, 2950MHz, 950MHz, 650MHz, 200MHz, and 100MHz) were used for analysis.
We used the data of more than 195 two-hour intervals before the high-power solar bursts. The information is divided into two groups: 110 events are related to the solar proton events, while 85 events were not accompanied by proton flux enhancement on the earth's orbit. A series of spectral/time features of precursors radio emission for proton and non-proton events is revealed: their ``broad-band", the time of their appearance before the onset of the pulse phase of the microwave burst, stability of characteristics during the different cycles of solar activity.
This work is supported by Russian Foundation for Fundamental Research and the Russian Federal Programme ``Astronomy".