Predicting Radiation Dose on Aircraft From Solar Energetic Particles

Predicting when solar energetic particles (SEPs) will hit Earth, and in what concentrations, is important to mitigating space weather hazards ranging from communications outages to high radiation levels on polar aircraft routes. In response to increasing public and scientific interest in better understanding radiation dose as solar cycle 24 ascends, a half-day session entitled “Predicting Radiation Dose From Solar Energetic Particles” was held during the Japan Geoscience Union 2011 International Symposium on 24 May. This was the first session held in Japan to discuss radiation hazards to aviation from SEPs and provided a unique starting point for an interdisciplinary approach. The main subject of this session was the radiation dose to airplane passengers from SEP events (Figure 1). About 50 participants attended the session, including solar-terrestrial researchers, radiological scientists, and airplane crews. Of the 15 research papers presented in the session, several evaluated current observations. For example, Kazuaki Asada (Air Line Pilots’ Association of Japan) talked about cosmic ray exposure during aircraft operation. He reported on various kinds of space weather influences that can affect aviation as well as the fact that the total dose to aviation from SEPs can be evaluated only after an event. In an invited talk, Seiji Yashiro (Catholic University of America and NASA Goddard Space Flight Center) evaluated automated detection techniques for important parameters of coronal mass ejections and flares in near real time. Several papers focused on SEPs and the Sun-Earth connection: Satoshi Inoue (Japan’s National Institute of Information and Communications Technology (NICT)) reported on the importance of characterizing the three-dimensional magnetic field structures around the Sun’s active regions to better understand the open magnetic field possibly connecting to the Earth, based on his nonlinear force-free-field technique. Mitsue Den (NICT) reported on the importance of seed particles for SEPs based on models of SEP acceleration at interplanetary shocks. Shinichi Watari (NICT) reviewed the paradigm of SEP acceleration via solar flares versus via shocks and noted important issues involved with how solar radio bursts associated with SEPs are generated. The remainder of the papers ranged from those that modeled the acceleration and propagation mechanisms of SEPs to ones that predicted the radiation dose in the atmosphere using real-time spacecraft and groundbased observations. Kyoko Watanabe (Japan Aerospace Exploration Agency) and Takashi Minoshima (Japan Agency for MarineEarth Science and Technology) reviewed the prediction capabilities of models that focus on flare acceleration of SEPs, and Takanobu Amano (Nagoya University) reviewed the prediction capabilities of the shock acceleration of