Space Weather Research: A Major Application of Imagery and Data Fusion

Space weather research involves the study of the Sun and Earth from a systems viewpoint to improve the understanding and prediction of solar-terrestrial variability. There are a wide variety of solar-terrestrial imagery, spectroscopic measurements, and in situ space environmental data that can be exploited to improve our knowledge and understanding of the phenomena and processes involved in space weather. 1. Space Weather Research The Sun is a magnetic variable star whose varying output of electromagnetic radiation, solar wind, and energetic particles generates variability in the geospace environment and upper terrestrial atmosphere. This variability, space weather, can affect a variety of human activities and technology such as spacecraft, GPS signals, electric power grid, high frequency radio signals, radiation exposures of astronauts in orbit and crews in high altitude aircraft, and is believed to be a major source of the natural variability in terrestrial climate. There is an international fleet of spacecraft observing the Sun and making measurements in the heliospheric environment between Sun and Earth and in the Earth’s space environment. Their observations of transient phenomena in the solar atmosphere along with the complementary observations and measurements of geospace variability are improving knowledge and understanding of the behavior of the connected Sun-Earth system. Relevant solar transient phenomena include solar flares, which can produce solar energetic particles and generate enhanced x-ray radiation affecting conditions in the terrestrial ionosphere, and coronal mass ejections (CME’s), which can cause geomagnetic storms when the ejected solar material reaches Earth. CME’s can also be a source of solar energetic particles. We are now able to probe not only the solar atmosphere, but also the solar interior. The latter is accomplished by using spectroscopic imaging data to measure the properties of waves at the solar surface to provide information on conditions in the solar interior via helioseismology techniques. This provides valuable information for developing models for the solar dynamo believed to be responsible for solar variability. The geospace environment is studied by in situ and remote sensing instruments on spacecraft orbiting Earth at a variety of altitudes and inclinations to observe the behavior of the terrestrial upper atmosphere and plasma and energetic particles in the Earth’s magnetosphere and its interface with solar wind flowing outward from the Sun. Interactions between the variable solar wind, solar energetic particles, and Earth’s atmosphere and magnetic field generate space weather phenomena such as aurorae and the radiation belts. The challenge is to develop techniques for optimally exploiting the diverse solar terrestrial data base to improve understanding of the characteristics and underlying physical processes of the phenomena involved in space weather. Much progress has been achieved as a result of simultaneous measurements of the variability of the Sun, heliosphere, and geospace provided by currently flying space missions. As a result of the fusion of these various types of data we now have much better insights as to what to measure with the next generation of solar terrestrial space missions and what new tools are needed for data fusion and analysis and the complementary theoretical modeling. For more information see reference [1] and the NASA Sun Earth Connection website (http://sec.gsfc.nasa.gov/).