LARGE SOLAR ENERGETIC PARTICLE EVENTS ASSOCIATED WITH FILAMENT ERUPTIONS OUTSIDE ACTIVE REGIONS

Solar Energetic Particle Events and Forbush Decreases Driven by the Same Solar Sources

The characteristics of Forbush decreases (FDs) and solar energetic particle (SEP) events driven by the same solar source (i.e., coronal mass ejection and associated solar flare) are investigated. The part of the solar disk (04∘ E–35∘ W) in which most of the solar events lead both to an FD and SEP event on Earth was chosen. SEPs for different energies (E > 10 MeV, E > 100 MeV, and Ground Level Enhancements) and with different flux thresholds were considered independently. The obtained results were compared with the control group of FDs that had solar sources within the same longitudinal zone but were not accompanied by any SEPs. It is shown that coronal mass ejections (CMEs) followed by SEPs have a very high probability of creating a large FD in the Earth’s orbit and to further cause a geomagnetic storm. It is also found that the accelerative and modulating efficiencies of powerful solar events are well correlated; this can be explained mostly by high speeds of the corresponding CMEs.

A Quarter Century of Wind Spacecraft Discoveries

The Wind spacecraft, launched on November 1, 1994, is a critical element in NASA’s Heliophysics System Observatory (HSO)—a fleet of spacecraft created to understand the dynamics of the Sun‐Earth system. The combination of its longevity (>25 years in service), its diverse complement of instrumentation, and high resolution and accurate measurements has led to it becoming the “standard candle” of solar wind measurements. Wind has over 55 selectable public data products with over ∼1,100 total data variables (including OMNI data products) on SPDF/CDAWeb alone. These data have led to paradigm shifting results in studies of statistical solar wind trends, magnetic reconnection, large‐scale solar wind structures, kinetic physics, electromagnetic turbulence, the Van Allen radiation belts, coronal mass ejection topology, interplanetary and interstellar dust, the lunar wake, solar radio bursts, solar energetic particles, and extreme astrophysical phenomena such as gamma‐ray bursts. This review introduces the mission and instrument suites then discusses examples of the contributions by Wind to these scientific topics that emphasize its importance to both the fields of heliophysics and astrophysics.

Wind has made seminal advances to the fields of astrophysics, turbulence, kinetic physics, magnetic reconnection, and the radiation belts

Wind pioneered the study of the source and evolution of solar radio emissions below 15 MHz

Wind revolutionized our understanding of coronal mass ejections, their internal magnetic structure, and evolution

High dose rates obtained outside ISS in June 2015 during SEP event

The R3DR2 instrument performed measurements in the European Space Agency (ESA) EXPOSE-R2 platform outside the Russian "Zvezda" module of the International Space Station (ISS) in the period 24 October 2014-11 January 2016. It is the Liulin-type deposited energy spectrometer (DES) (Dachev et al., 2015a). Took place in November 2014, this was the first attempt to monitor a small solar energetic particle (SEP) event outside ISS using the Liulin-type DES (Dachev et al., 2015d). In this study, we describe the dosimetric characteristics of the largest SEP event, observed on 22 June 2015 with the R3DR2 instrument outside ISS. The main finding of this study is that SEP protons with a minimum energy of approximately 7MeV at the surface of the R3DR2 detector produced high dose rates, reaching >5000µGyh(-1), while the inner radiation belt maximum dose was at the level of 2200µGyh(-1). If a virtual external vehicle activity (EVA) was performed in the same period of the SEP maximum on 22 June 2015, the doses obtained in the skin of cosmonauts/astronauts can reach 2.84mGy after 6.5h, which is similar to the average absorbed dose inside ISS for 15days (Reitz et al., 2005). A comparison with other extreme events measured with Liulin-type instruments shows that SEPs similar to that observed on 22 June 2015 could be one of the most dangerous events for the cosmonauts/astronauts involved in EVA.