Multidisciplinarity in Research of Extreme Solar Energy Influences on Natural Disasters

The atmosphere is a very sensitive medium to extraterrestrial forces, most importantly, solar electromagnetic radiation and energetic particle intrusion. This released intense solar activity can cause sudden disturbances in the Earth’s atmosphere and further create ground telecommunication interferences, blackouts, transportation problems, water supply problems, potential health effects, as well as natural disasters, such as forest fires. These extreme events can cause billions of dollars of damage and impact individuals, families, communities, and societies. For this reason, it is of crucial importance to investigate the connections between this extreme activity and natural disasters, and further develop ways to prevent, prepare against, and respond to them. The aim of this special issue is to engage a wide community of scientists to de-fragment broaden and improve our knowledge in this field. We invite researchers from all relevant fields to publish their recent investigations in this special issue.

Sun and planets from a climate point of view

The Sun plays a dominant role as the gravity centre and the energy source of a planetary system. A simple estimate shows that it is mainly the distance from the Sun that determines the climate of a planet. The solar electromagnetic radiation received by a planet is very unevenly distributed on the dayside of the planet. The climate tries to equilibrate the system by transporting energy through the atmosphere and the oceans provided they exist. These quasi steady state conditions are continuously disturbed by a variety of processes and effects. Potential causes of disturbance on the Sun are the energy generation in the core, the energy transport trough the convection zone, and the energy emission from the photosphere. Well understood are the effects of the orbital parameters responsible for the total amount of solar power received by a planet and its relative distribution on the planet's surface. On a planet, many factors determine how much of the arriving energy enters the climate system and how it is distributed and ultimately reemitted back into space. On Earth, there is growing evidence that in the past solar variability played a significant role in climate change.

Top-side ionosphere response to extreme solar events

Strong X-flares and solar energetic particle (SEP) fluxes are considered as sources of topside ionospheric disturbances observed by the ROCSAT-1/IPEI instrument during the Bastille Day event on 14 July 2000 and the Halloween event on 28 October–4 November 2003. It was found that within a prestorm period in the dayside ionosphere at altitudes of ~600 km the ion density increased up to ~80% in response to flare-associated enhancements of the solar X-ray emission. Ionospheric response to the SEP events was revealed both at sunlit and nightside hemispheres, where the ion density increased up to ~40% and 100%, respectively. We did not find any prominent response of the ion temperature to the X-ray and SEP enhancements. The largest X-ray and SEP impacts were found for the X17 solar flare on 28 October 2003, which was characterized by the most intense fluxes of solar EUV (Tsurutani et al., 2005) and relativistic solar particles (Veselovsky et al., 2004). Solar events on 14 July 2000 and 29 October 2003 demonstrate weaker impacts with respect to their X-ray and SEP intensities. The weakest ionospheric response is observed for the limb X28 solar flare on 4 November 2003. The topside ionosphere response to the extreme solar events is interpreted in terms of the short-duration impact of the solar electromagnetic radiation and the long-lasting impact of the SEP.