Posters on site: Wed, 6 May, 16:15–18:00 | Hall X4
An one-dimensional fluid model is presented which describes the generation of type III radiation as an antenna problem at which the triggering current pulse imitates the temporal evolution of the beam instability. The mechanism works without the involvement of the classical plasma emission via the parametric processes and the coalescence of waves. After linearization of the Maxwell-fluid equations and Fourier transform in space, the system of nine differential equations describing the temporal evolution of the fluid and electromagnetic quantities is solved numerically. It is shown that the commonly observed beating structure of the electromagnetic radiation in form of a double-peak in their spectra, commonly explained by parametric decay of the beam-excited Langmuir wave, is caused by the superposition of two wave modes of mixed polarisation (Langmuir/z wave) which belong the wave number of optimum mode coupling. Within in the same formalism the generation of the second harmonic of the electromagnetic radiation is calculated by taking into account the nonlinear currents as product of the first-order terms. Satellite observations of beam-excited Langmuir waves and solar type III radiation are discussed in the light of the presented antenna model.
How to cite: Sauer, K. and Liu, K.: Solar type III radiation as antenna problem - Electromagnetic wave generation by the beam-driven electron current, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13785, https://doi.org/10.5194/egusphere-egu26-13785, 2026.
The Solar Radio Monitoring website (secchirh.obspm.fr) serves as a hub for the combined visualisation of solar radio data, specifically designed to support multi-wavelength analysis of solar activity and its complex solar-terrestrial relationships. Through the integration of high-resolution ground-based observations from the Nançay Radio Heliograph (NRH) with dynamic spectra from a wide range of instruments operating across the globe (ORFEES, NDA, HUMAIN, Gauribidanur, Culgoora, learmonth, Yunan and Arthemis), as well as hectometric and kilometric measurements from space missions such as WIND, and STEREO, the website provides a continuous and global view of the solar environment, from the low corona to the interplanetary medium. This multi-instrument synergy is further strengthened by the integration of Solar Orbiter’s instruments. In particular, STIX delivers quantitative X-ray measurements that trace accelerated electrons in active regions, EPD characterizes ions and suprathermal particles up to several hundred MeV per nucleon, while RPW (Radio & Plasma Waves) provides measurements of the surrounding radio and plasma wave environment. These measurements enable researchers to track the propagation of these particles through the solar corona and interplanetary space. By integrating these diverse datasets, the website facilitates fast visualization of particle acceleration and transport processes and provides indispensable tools to both experts and the broader scientific community for fundamental heliophysics research and the improvement of space weather forecasting models. This contribution presents the latest developments of the Solar Radio Monitoring website, with a particular focus on recent enhancements in multi-instrument data integration and visualization tools.
How to cite: Hamini, A. and Romagnan, R.: Radio Monitoring and Solar Radio Orbiter Instruments: tools for fast access to space and ground-based radio observations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19375, 2026.
We present a study of fine time–frequency structures and their complex temporal evolution in the narrowband (NB) and wideband (WB) components of Jupiter’s sporadic decametric (DAM) emission, including cases where both components appear simultaneously in dynamic spectra. High-resolution observations of a Jovian radio storm on 26 November 2009, featuring emission from Io-C and Io-A″ sources, were recorded with the UTR-2 telescope (8–32 MHz) using a baseband digital receiver, enabling waveform acquisition suitable for offline multi-scale analysis. Spectral images were produced with a custom multi-scale algorithm incorporating high-pass filtering to suppress narrowband radio frequency interference (RFI) while preserving intrinsic Jovian signals. Windowed Fourier transforms traced the formation, temporal evolution, and internal structure of NB events and their relation to classical S- and L-bursts. Some NB events exhibit complex patterns requiring interpretations beyond standard classifications. Combined with spacecraft observations from Juno and the forthcoming JUICE mission, these data allow disentangling intrinsic emission physics from propagation effects. In particular, the analysis demonstrates the potential to study emissions arriving simultaneously from two spatially separated sources with different polarization. Future studies, combining high-resolution spectra from UTR-2, GURT, LOFAR, NenuFAR, NDA, LWA, and other instruments with spacecraft measurements, will further enable identification and characterization of modulation patterns in Jupiter’s DAM waves. These results provide constraints for DAM generation models, emphasize the value of polarization-resolved, high-resolution studies, and support the identification of emission sources and plasma media along the propagation path.
How to cite: Litvinenko, G., Ryabov, V., Rothkaehl, H., and Zakharenko, V.: Study of the Jovian Decameter Narrow- and Wideband Emission: Fine Time–Frequency Structures and Temporal Evolution, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17286, 2026.
The study presented here is a continuation of a series of works where the angular distribution of the Jovian decameter radiation occurrence probability, relatively to the local magnetic field B and its gradient ∇B in the source region is investigated, using the recent magnetic field model for Jupiter, based on Juno’s first 33 polar orbits observations, Jupiter Refence Model JRM33, proposed by Connerney et al. [Journal of Geophysical Research: Planets, 127, 1-15, 2022]. Our results are compared to those obtained earlier using the JRM09 model derived from the first nine orbits of the Juno spacecraft by Connerney et al. [Geophysical Research Letters, 45, 2590-2596, 2018]. The JRM33 model confirms the former findings where the radio emission is beamed in a hollow cone exhibiting a flattening in a specific direction. The Jovian decameter radiation is supposed to be produced by the cyclotron maser instability (CMI). We interpret this flattening by the fact that the magnetic field in the radio source does not have any axial symmetry because B and ∇B are not parallel. This assumption is confirmed by the amplitude of the flattening of the cone which appears to be more important for the northern emission (31.8%) than for the southern one (11.4%) probably due to the fact that the angle between the directions of B and ∇B is greater in the North (~10°) than in the South (~5°). We propose a theoretical study of the propagation and amplification of the waves by the CMI in the radio source in the plane (B, ∇B) as well as in the perpendicular plane aiming to evaluate the emergence angle of the radiation.
How to cite: Galopeau, P. and Boudjada, M.: Contribution of JRM33 model to the study of emission cone of Jovian decameter radiation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13922, https://doi.org/10.5194/egusphere-egu26-13922, 2026.
We investigate Type III solar radio bursts observed by the radio and plasma wave experiment (RPWS) onboard Cassini spacecraft (Galopeau et al., 2007) in the period from January 2004 to September 2017. In this time interval of about thirteen years an important number of solar Type III bursts has been recorded. We consider in this work the remote sensing of the Saturn’s magnetosphere environment using the daily RPWS dynamic spectra in the frequency range from 1 Hz to 16 MHz. In spite of the enormous distance between the Sun and Saturn, in the order of ~ 1.5 109 km, this instrument detected Type III bursts superposed to magnetospheric auroral activity emitted by Saturn (Boudjada et al., 2023). We underline in this analysis on particular solar radio bursts which exhibit saturated intensity levels, like the Saturnian kilometric radiation (SKR). We attempt to discuss the origin of the saturated and boosted Type III bursts, drifting rapidly from high to low frequencies, and considered to be generated in the solar corona following Archimedean spiral linked to the solar magnetic field expansion in the interplanetary medium.
References:
Boudjada et al., Statistical analysis of Solar Type III radio bursts observed by RPWS experiment in 2004-2017 during the Solar cycles 23-24. In Proceedings Kleinheubach Conference, Ed. U.R.S.I. Landesausschuss in Deutschland e.V., IEEE, Miltenberg, 2023.
Galopeau et al., Spectral features of SKR observed by Cassini/RPWS: Frequency bandwidth, flux density and polarization. Journal of Geophysical Research, 112, A11, 2007.
How to cite: Boudjada, M. Y., Galopeau, P. H. M., Lammer, H., Lecacheux, A., and Rucker, H.: Solar activity at Saturn’s magnetosphere environment: Case study of Type III radio bursts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20595, 2026.
Saturn kilometric radiation (SKR) is mostly a fully circularly polarized radio emission from Saturn's auroral region. However, Fischer et al. (2009, doi:10.1029/2009JA014176) found that SKR can show a linear component and be elliptically polarized, and this SKR property is typically found above observational latitudes of about 30 degrees (in both hemispheres). Using all available RPWS (Radio and Plasma Wave Science) data throughout the Cassini mission, we calculated mean polarization properties (linear, circular, total) of SKR for each hour in the frequency range from 100 to 1200 kHz. This revealed transitional latitudes from 20 to 40 degrees in which the linear polarization degree of SKR rises from around 0.1 (which is the usual error for the polarization measurement) up to 0.6. Furthermore, we found that SKR shows a lower total polarization degree at the transitional latitudes.
We will try to give a reason for this unexpected behavior. We will also show comprehensive meridional plots of SKR circular, linear, and total polarization to understand the polarization properties of this important Saturnian radio emission.
How to cite: Fischer, G., Jost, D., Taubenschuss, U., Pisa, D., Cecconi, B., Lamy, L., and Kurth, W.: Analysis of elliptical polarization of Saturn kilometric radiation throughout the Cassini mission, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6325, https://doi.org/10.5194/egusphere-egu26-6325, 2026.
