a) Correlation curve for the polarization channel (NoRH, 17 GHz) during daytime observations. The horizontal lines shows the interval before the flare (burst) at 03:30–05:55 UT (1) and at the post-flare stage, at 05:55–06:30 UT (2). b) 3-min variation of correlation coefficients with removed low-frequency trend. The 3σ error bar is added. c) Power variation of correlation coefficients centred at 3-min period. d) Wavelet power spectrum of oscillations. The flare (burst) maximum is shown by vertical broken line.