Simulating effects of the 774 AD solar proton event on atmospheric electricity

<p>High energy cosmic rays of galactic and solar origin, natural radioactivity, lighting in thunderstorms and electrified shower clouds, produce ion clusters and charge the whole atmosphere causing a ubiquitous potential difference between the ionosphere and the surface. This Global Electric Circuit (GEC) allows the flow of charges to the surface in the fair-weather regions of the globe. Here, we simulate the effect of highly energetic particle radiation, in particular the 774 AD solar proton event, on the GEC with the aid of the global circulation model EMAC/MESSy. The simulations assume pre-industrial atmospheric conditions and the coupling of aerosol and atmospheric electricity schemes allows for ion-ion and ion-aerosol capture reactions. We discuss effects in fair weather current and atmospheric conductivity at different latitudinal bands. </p>

МЕТОДЫ СОГЛАСОВАНИЯ ВАРИАЦИЙ И АСТРОФИЗИЧЕСКИХ МАРКЕРОВ В СРЕДНЕВЕКОВОЙ АРХЕОЛОГИИ

Application of the modifications of the radiocarbon method are presented that allowed accurate dating of archaeological sites of the 1st millennium AD. The use of wiggle-match dating on tree rings from the excavations of the settlement of Gnezdovo on the upper Dnieper made it possible to date the foundation of the settlement to the end of the 8th century AD, a century older than previously existing ideas. Identification in tree rings of the AD 775 solar proton event («Miyake event») made it possible to date the construction of the walls of the ancient Uigur complex Por-Bajin with an accuracy of up to a year, and in combination with dendrochronological data – up to the season: summer AD 777, over a quarter of century younger than the previously accepted date (AD 750). Together with the historical context, this helped to confirm the hypothesis that the building has a cult purpose rather than a fortification (a Manichean monastery).

Prediction of Solar Proton Event Fluence spectra from their Peak flux spectra

Solar Proton Events (SPEs) are of great importance and significance for the study of Space Weather and Heliophysics. These populations of protons are accelerated at high energies ranging from a few MeVs to hundreds of MeVs and can pose a significant hazard both to equipment on board spacecrafts as well as astronauts as they are ionizing radiation. The ongoing study of SPEs can help to understand their characteristics, relative underlying physical mechanisms, and help in the design of forecasting and nowcasting systems which provide warnings and predictions. In this work, we present a study on the relationships between the Peak Flux and Fluence spectra of SPEs. This study builds upon existing work and provides further insights into the characteristics and the relationships of SPE Peak flux and Fluence spectra. Moreover it is shown how these relationships can be quantified in a sound manner and exploited in a simple methodology with which the Fluence spectrum of an SPE can be well predicted from its given Peak spectrum across two orders of magnitude of proton energies, from 5 MeV to 200 MeV. Finally it is discussed how the methodology in this work can be easily applied to forecasting and nowcasting systems.