Assessing the spectral characteristics of band splitting type II radio bursts observed by CALLISTO spectrometers

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Assessing the spectral characteristics of band splitting type II radio bursts observed by CALLISTO spectrometers

Minta, Felix N. / Nozawa, Satoshi I. / Kozarev, Kamen / Elsaid, Ahmed / Mahrous, Ayman

Abstract Metric type II radio bursts are usually early indicators of CME-driven shocks and other space weather phenomena in the solar corona. This paper presents a detailed investigation of the spectral properties of band splitting type II radio bursts and their association with sunspot number. Using type II radio bursts in a frequency range [20 MHz–200 MHz] observed by CALLISTO during 2010–2017, it was discovered that the analyzed type II shock height, magnetic field strength, CME/shock speed, and Alfvén speed synchronize with the trajectory of the solar cycle 24. Also, the study revealed that the onset of the declining phase of solar cycle 24 has the highest electron density, whiles the frequency of type II bursts depicts a bimodal distribution during the study period, with peaks in 2012 and 2015. Further, a good correlation (with correlation factor R = 0.87) was obtained between the estimated CME/shock speeds from the dynamic spectra and the associated CME speeds from SOHO/LASCO. Moreover, the study confirmed a significant correlation (R= ∼0.8) between the absolute drift rates and the plasma frequency. Additionally, the study explored that ∼ 60% of the type II radio bursts considered in this study emanated from the western longitudes. Hence, the findings emphasize that the temporal dynamics of the physical conditions of band splitting type II radio bursts are essential parameters for space weather monitoring and forecasting.