Solar radio bursts (SRBs) are sudden peaks in the low-frequency radio emissions originating from the sun. These emissions can also help predict space weather events that could have adverse effects on satellite communications and the global energy grid. A thorough understanding of this phenomenon demands the collection and analysis of solar emission data over vast geographical and time scales. In this regard, the e-CALLISTO network plays a major role through having already archived more than 20 years’ worth of SRB data. Leveraging on the advances in data analysis techniques, this data can be ..read more

Inelastic scattering off moving or oscillating density fluctuations leads to broadening of radio signals propagating in the solar corona and solar wind. Using an anisotropic density fluctuation model from the kinetic scattering theory for solar radio bursts, we deduce the plasma velocities (perpendicular to the line of sight) required to explain observations of spacecraft signal frequency broadening. The kinetic energy associated with these inferred bulk velocities cascades to smaller and smaller scales, where it is ultimately dissipated through damping of ion-sound waves. The inferred energ ..read more

Here we release the spectral data of solar radio bursts recorded by the Chashan Broadband Solar radio spectrograph (CBSm), located in the Chashan mountain (E122°.30, N36°.84) that is the southern tip of Shandong Peninsula of China. CBSm is supported by the Chinese Meridian Space Weather Monitoring Project (II) and Shandong University. It is designed and operated by the Laboratory for ElectromAgnetic Detection of Institute of Space Sciences (LEAD, ISS), Shandong University. CBSm observes the Sun from 90 to 600 MHz with a 12m parabolic antenna fed by a dual-polarization LPDA feed. Its receiver ..read more

Polarization, regardless of wavelength, is one of the key observables for understanding the solar atmosphere because it provides information about magnetic fields, and microwave polarization is also one of them. It can reveal magnetism in the chromosphere, transition region, and corona from the microwave polarization dependencies of opacity and emissivity related to magnetic fields. Although observing solar polarization in the microwave range is not easy, it has a long history since the early days of solar radio observations (e.g., Tanaka and Kakinuma 1957). Recently, we have published ..read more

Since the discovery of solar radio emission in the late 1940s, the Sun has been studied in great detail across a wide range of frequencies from a few tens of kHz to several hundreds of GHz. Solar radio emissions provide several unique diagnostics of the solar corona, which are otherwise simply inaccessible. Despite this long history of observations and studies, the Sun still harbors several mysteries. Improved observations from the new telescopes enabled by technological advances help solve these mysteries. At the same time, these new advancements probe the Sun in ways not possible earlier ..read more

The study of solar wind acceleration and coronal heating has been a major challenge in solar physics. The main difficulty is that the collisionless characteristic of high-temperature, thin, and fully ionized coronal plasmas lead to the heating and acceleration of the coronal plasmas to be dominated by wave particle interactions, which are the “elementary processes” of the plasma collective interaction at the kinetic scales of plasma particles. Radio observation becomes main information sources of the coronal plasmas, instead of the spectral line observation, which is a main method of inferri ..read more

The turbulent heliosphere has a significant effect on the observed characteristics of radio emission produced in, or viewed through, the solar atmosphere. In particular, radio-wave scattering on density irregularities can broaden the observed decay times and source sizes, and shift the apparent source position. Both radio burst observations and simulations have demonstrated that the turbulence is anisotropic, which can explain both the observed decay times and source sizes simultaneously. Considering that the same density turbulence modifies extra solar and solar sources, and the density flu ..read more

Recent years, several new generation solar radio telescopes operating in the centimeter decimeter (dm-cm) wavelengths have emerged in the world, including the Mingantu Spectral Radioheliograph (MUSER, 0.4-15GHz) (Yan et al. 2021), the Expanded Owens Valley Solar Array (EOVSA, 1-18GHz) (Gary et al. 2018), and the Siberian Radio Heliograph (SRH, 3-24GHz) (Altyntsev et al. 2020). Due to the fact that the solar radio emission in dm-cm wavelengths mainly originates from the solar burst source region and the primary propagation region of released energy and accelerated high-energy particles, the o ..read more

Density turbulence in the solar corona and solar wind is evident via the properties of solar radio bursts; angular scattering-broadening of extra-solar radio sources observed through the solar atmosphere, and can be measured in-situ in the solar wind. A viable density turbulence model should simultaneously explain all three types of density fluctuation observations. Solar radio bursts (e.g. Type I, II, III) observed below ~1 GHz are produced predominantly via plasma mechanisms at frequencies that are close to either the local plasma frequency or its double (harmonic), and are thus particular ..read more

Coronal mass ejections (CMEs) are large-scale expulsion of plasma and magnetic fields from the solar corona into the heliosphere. Magnetic field entrained in the CME plasma is crucial to understand their propagation, evolution, and geo-effectiveness. Among the different observables at radio wavelengths, spectral modeling of faint gyrosynchrotron (GS) emission from CME plasma has been regarded as one of the most promising remote observing techniques for estimating spatially resolved CME magnetic fields. Imaging the very low flux density CME GS emission in close proximity to the Sun with order ..read more