| dc.description.abstract | The main purpose of this thesis is to discuss the features of the pre-flare Quasi-Periodic Pulsation (QPP) in multiple wavelength including the radio, extreme ultraviolet (EUV) and soft X-ray (SXR).
QPP is thought to be the nature of solar flares, which can be observed during and before flares in various wavelengths, such as the radio, microwave, EUV, and SXR. The period of QPP may vary with time or present several periods in the same time.
In Tan et al. (2016), we select five pre-flare QPP events. To analyze any possible period, we use the radio data in the frequency from 2.81 to 2.85 and from 2.91 to 2.95 GHz in the Solar Broadband Radio Spectrometer (SBRS) and then to compare with the period of SXR from Geostationary Operational Environmental Satellites (GOES). At the beginning, based on the result of Fast Fourier Transformation (FFT), both the period in radio and SXR are not obvious on the significance level of 99.7%, which were all similar in the five events. However, if use wavelet, we are able to spot the periods successfully in three out of five events, which are the event on 22nd September 2011, 15th October 2012 and 13th May 2013.
We select the event on 15th October 2012 which has the most obvious results in radio based on the wavelet analysis, choosing four certain areas based on Fe XVIII images and plotting the lightcurve of each area in 211 Å. Then, we mark the QPP signal of EUV and radio on the wavelet of SXR and find it mostly above normalization power 0.8 in the SXR wavelet result. We thus suggest that the pre-flare QPP in this event can be manifested in both of the thermal (SXR and EUV) or non-thermal (radio) radiation processes.
In the other two events in 22nd September 2011 and 13th May 2013, we mark the QPP signal of radio on SXR wavelet result, but the time interval above normalization power 0.8 only takes 1/4 the time of analysis.
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