Observations of a radio-quiet solar preflare
by A. Benz et al.*

2017-10-17 286 views

A substantial fraction of the flare energy (as observed e.g. in bolometric luminosity) first appears in non-thermal electrons and ions (Emslie et al. 2012). It implies that the particles are efficiently accelerated to a non-Maxwellian velocity distribution. Most of the non-thermal electrons have energies in the 10 – 30 keV range, but some are accelerated beyond 100 keV and radiate gyro-synchrotron radio emission. Nearly all of the flare energy is […]

Predicting Flares and Solar Energetic Particle Events: The FORSPEF Tool
by A. Anastasiadis et al.*

2017-10-10 401 views

A novel operational open-access forecasting system that provides reliable forecasting and nowcasting of solar energetic particle (SEP) events, as well as forecasting of solar flares (SFs) based on precursor information, is presented. FORSPEF offers continuous forecasts and nowcasts of SFs and SEP events, up to 70◦ E/W covering practically the entire course of an active-region (AR) toward the limb (up to ~85◦). The prediction window in the forecasting scheme is […]

Exploring the potential of microwave diagnostics in SEP forecasting
by P. Zucca et al.*

2017-10-03 281 views

Solar energetic particles (SEPs), especially protons and heavy ions, may be a space-weather hazard when they impact spacecraft and the terrestrial atmosphere. Forecasting schemes have been developed, which use earlier signatures of particle acceleration to predict the arrival of solar protons and ions in the space environment of the Earth. The UMASEP (University of MAlaga Solar particle Event Predictor) scheme (Núñez 2011), forecasts the occurrence and the importance of an […]

Solar plasma radio emission and inertial Alfvén turbulence
by O. Lyubchyk et al.*

2017-09-26 428 views

We study the influence of kinetic-scale Alfvénic turbulence on the generation of plasma radio emission in the solar coronal regions where the plasma/magnetic pressure ratio $\beta $ is smaller than the electron/ion mass ratio $m_{e}/m_{i}$. The present study is motivated by the phenomenon of solar type I radio storms associated with the strong magnetic field of active regions. The measured brightness temperature of the type I storms can be up […]

EUV-invisible reservoir of solar energetic particles
by G. Fleishman et al.*

2017-09-19 444 views

Large-scale magnetic structures, which likely make a “bridge” between the relatively compact particle acceleration site of a flare energy release and the interplanetary medium, are of particular importance because of their potential role as an “escape route” for solar energetic particles (SEPs). Although these escape routes can sometimes be associated with jets visible in extreme ultraviolet (EUV) and/or soft X-rays (SXRs), the jet plasma must be dense enough to be […]

Oscillations in the 45-5000 MHz Radio Spectrum of the 18 April 2014 Flare
by M. Karlicky et al.*

2017-09-05 518 views

Recently, oscillations were recognized in the global X–ray flux detected during the 18 April 2014 M7.3 flare by the Fermi/GBM instrument as well as in the spatially localized UV measurements of the IRIS satellite and the EIS/Hinode instruments (Brosius and Daw, 2015, Brosius, Dawn and Inglis, 2016, and Brannon, Longcope, and Qiu, 2015). Radio observations of this flare were also analyzed by Carley, Vilmer, and Gallagher (2016). The overall radio spectrum […]

Traveling Ionospheric Disturbances as Huge Natural Lenses: Solar Radio Emission Focusing Effect
by A. Koval et al*

2017-08-29 3,246 views

The solar radio emission in meter-decameter wavelengths demonstrates a plentiful variety of solar radio bursts of different types (with branching to sub-types) as well as events not belonging to any specific type (Melnik et al. 2005). The last group includes variable solar emissions that result from radiation processes affected by propagation effects in the terrestrial ionosphere. Particularly, low-frequency solar radiation passing through the ionosphere could be subject to different influences […]

Wavelet-based characterization of small-scale solar emission features at low radio frequencies
by A. Suresh et al.*

2017-08-15 595 views

The improved sensitivity provided by new-generation radio arrays has unveiled an enormous diversity of previously under-appreciated solar radio bursts. Observations in the 100-240 MHz band using the Murchison Widefield Array (MWA) have highlighted the presence of a myriad of weak, short-lived, narrow-band solar emission features (Fig. 1), even during calm solar periods. Their appearance in the MWA solar dynamic spectrum (DS) comes closest to miniature versions of type-III bursts with […]

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