The short-term prediction of solar proton events based on a distinct U-shaped radio burst signature is verified. The prediction techniques uses peak flux density values of discrete frequency solar radio burst observations in the 100 to 10,000 MHz region. The criteria are applied to all major proton events from 1952 to 1969 and afford almost total success in predicting near-earth particle events that eminated from visible hemisphere regions of the sun. A correlation between U-shaped radio burst signatures and solar proton events as detected by the ATS-1 satellite, during 1967 and 1968, is also shown to be highly successful. Finally, a 'modified' U-shaped criterion is set forth for the accurate short-terms prediction of polar cap absorption events that result in at least a 2.0 dB riometer measurement of absorption. This 'modified' spectral configuration is then correlated with the major absorption events of the current solar cycle and it is found that prediction occurred for all principal PCA events that originated from visible solar hemisphere flares. (Author).

As a star in the universe, the Sun is constantly releas- cover a wide range of time and spatial scales, making ?? ing energy into space, as much as ?. ? ?? erg/s. Tis observations in the solar-terrestrial environment c- energy emission basically consists of three modes. Te plicated and the understanding of processes di?cult. ?rst mode of solar energy is the so-called blackbody ra- In the early days, the phenomena in each plasma diation, commonly known as sunlight, and the second region were studied separately, but with the progress mode of solar electromagnetic emission, such as X rays of research, we realized the importance of treating and UV radiation, is mostly absorbed above the Earth’s the whole chain of processes as an entity because of stratosphere. Te third mode of solar energy emission is strong interactions between various regions within in the form of particles having a wide range of energies the solar-terrestrial system. On the basis of extensive from less than ? keV to more than ? GeV. It is convenient satellite observations and computer simulations over to group these particles into lower-energy particles and thepasttwo decades, it hasbecomepossibleto analyze higher-energy particles, which are referred to as the so- speci?cally the close coupling of di?erent regions in the lar wind and solar cosmic rays, respectively. solar-terrestrial environment.

Solar energetic particles (SEPs) emitted from the Sun are a major space weather hazard motivating the development of predictive capabilities. This book presents the results and findings of the HESPERIA (High Energy Solar Particle Events forecasting and Analysis) project of the EU HORIZON 2020 programme. It discusses the forecasting operational tools developed within the project, and presents progress to SEP research contributed by HESPERIA both from the observational as well as the SEP modelling perspective. Using multi-frequency observational data and simulations HESPERIA investigated the chain of processes from particle acceleration in the corona, particle transport in the magnetically complex corona and interplanetary space, to the detection near 1 AU. The book also elaborates on the unique software that has been constructed for inverting observations of relativistic SEPs to physical parameters that can be compared with space-borne measurements at lower energies. Introductory and pedagogical material included in the book make it accessible to students at graduate level and will be useful as background material for Space Physics and Space Weather courses with emphasis on Solar Energetic Particle Event Forecasting and Analysis. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.

A catalog of about 118 proton events, 1966-1976, not included in an earlier catalog of 81 events (AFGL TR-77-0081) for the same period is presented. These 118 events combined with the earlier 81 provide the basis for summarizing solar radio burst/high-energy proton correlation and prediction signature work. In the earlier effort, hereafter called Catalog I, the starting point was the identification of all solar radio bursts having the classical U-shape spectrum, and then establishing proton event association for the purpose of devising a reliable 'false-alarm' free predictor of the major proton events (equivalent PCA 2-2. 5dB). In the present effort, the starting point is the identification of all other proton events not included in Catalog I (misses by the U-shape spectrum criteria), and then searching for the establishing solar radio correlations and possible predictions of weaker proton events. There are very few real misses of principal proton events.