A1S1

We live in an era when the concept of environment is enormously extended. It is not bound to the accessible terrestrial sites, oceans and atmosphere, but it also comprises the extraterrestrial environment including the Sun. What we observe in this expanded and dynamic environment is called Space Weather. Influences of the Sun on the Earth come through the solar spectrum of radiation, which provides us with light and heat, and through other changing features of the solar activity.

Some of the most important and impressive phenomena of the solar activity are shown in the figures below depicting sunspots (regions of intense magnetic fields on the solar surface) and coronal mass ejections (CMEs). CMEs carry tremendous amounts of plasma and energy through the solar system, and those which hit the Earth can, in some cases, lead to dramatic consequences. When a CME reaches the Earth, complex series of events in the magnetosphere and ionosphere are triggered, with effects down to the lower atmosphere and on the ground.

SOTERIA, a new FP7 Space Science project, aims at improving our understanding of the space weather phenomena through collaboration between experts in different fields of solar, space, and geophysics. The main goal is to make better use of existing data and provide better databases, which will go beyond the present state-of-the-art in regard to details, time-resolution and improved methods of accessing it.

The studies conducted by SOTERIA involve the analysis and processing of the relevant data from 18 satellites, including several ESA and other European satellites. The study is complemented by a large set of data from European ground-based observatories. SOTERIA includes also considerable effort in utilizing and developing theoretical and simulation models for interpreting the space weather data.

As an example of the modelling activities, the figure below shows the results of one simulation of the process called magnetic reconnection, which is at the heart of many space weather phenomena. Magnetic fields get annihilated in localized regions and their energy is released into the space environment.

The activities covered by SOTERIA cover all aspects of the complex Sun-Earth connection.

Photosphere and Chromosphere. Starting at the source of the space weather events, the first activity area focuses on the solar photosphere and chromosphere, that are the lowest visible strata of the Sun. The activities developing there are largely determined by what happens under the visible surface, in the interior of the Sun, an area that can currently be explored by helioseismology a discipline that uses wave activities on the visible surface to detect the underlying structures (similar in principle to the seismology studies done on the Earth for example to detect underground oil reservoirs). SOTERIA collects all the available type of information on the photospheric and chromospheric features of the Sun relevant to space weather.

Global changes in the solar activity are characterized by an 11-year cycle. The last cycle has finished recently with its lowest level of activity, and now the new cycle is to begin with an increasingly active phase coming, making the study of space weather even more urgent. Significant puzzlement is currently stirring the community due to the apparent delay in the start of the next phase of increased solar activity, an issue where the historic data collected as part of the SOTERIA project will prove valuable.

Solar Corona. The next layer of the solar atmosphere is the corona, visible by the unaided eye during solar eclipses as a crown around the Sun, giving it its name. SOTERIA focuses on bringing to bear the full range of observational tools on the ground and on satellites, including new and planned missions, and of theoretical and simulation tools to advance our ability to understand and predict the dynamic processes of the solar corona, such as the streamers, the flares and the eruptive evolution of solar arcades leading to the so-called CME, coronal mass ejection.

Heliospheric Evolution. The solar wind emanating from the Sun carries with it the solar magnetic field and the disturbances caused by the dynamic events on the Sun. The interaction of this complex medium with the planets and especially of course with the Earth is at the core of the study of space weather. The SOTERIA project uses dedicated existing tools, observational and theoretical, to understand this interaction. A catalog of events covering some of the most common and most interesting occurrences in the space weather is created and a large collaborative effort is made to investigate with all tools available (some of which are in collaboration with American institutions, such as the Community Coordinated Modelling Center of NASA) and by all teams with expertise in this field within SOTERIA. But we also are developing new tools to harness the expertise of some SOTERIA partners in other areas of environmental forecasting (such as the meteorological predictions or the ocean modelling). We are developing a new statistical approach to couple observational data into theoretical simulations (the so-called data assimilation) to improve the predictive capability.

Irradiance. Of course the solar influence on the Earth and space is not limited to the solar wind, also the light comes from the Sun! An accurate estimation of the effects of solar events and natural solar cycles is key in our understanding of the Sun-Earth connection, with implications also for the complete understanding of the mechanisms constraining the climate. In SOTERIA, we focus on the variability and the origin of the UltraViolet radiation, which is likely to play a major role in the Sun-climate connection, and also develop models to understand its impact on the upper atmosphere.

Finally SOTERIA puts the largest emphasis on making all the models and all the observations described above available not only in their raw format but in a more organized common frame that maximizes the value of data previously scattered and presented incoherently. As part of this effort, SOTERIA does not only rely on state of the art internet-based software tools (including both software tools developed by the USA research efforts and by other European efforts such as the FP7 project HELIO) but will also organize outreach for the general public and training for scientists, in collaboration with other European efforts, funded by COST and international institutions such as the UNESCO International Center for Theoretical Physics, targeting especially to reach young scientists in developing countries.

The team of the SOTERIA project is coordinated by Giovanni Lapenta of the Katholieke Universiteit Leuven and includes scientists from institutions in 8 EU countries (Belgium, Denmark, Germany, Austria, Hungary, France, Poland, Finland) and in 3 non-EU countries (Switzerland, Croatia and Russia). The web site for SOTERIA is www.soteria-space.eu.

Figure Captions

1) Image of the Suns surface showing the presence of sunspots (areas of intensified magnetic fields).

2) Image of the solar corona showing the presence of active regions that lead to emission of matter and energy (coronal mass ejections, CMEs).

3) Simulation of magnetic reconnection, the process of magnetic field annihilation and energy release into the space environment. Simulations conducted by the KU Leuven beneficiary in collaboration with Stefano Markidis of University of Illinois and with the NASA MMS Mission. Some of the fastest computers in Europe and the USA were used, including NASA's Pleiades and the Vlaams Supercomputer Centrum.