Ionospheric variability (space weather) significantly impacts ground and space-based communications. In essence, the electrically charged particles of the ionosphere (i.e., the partially ionized portion of the atmosphere starting at about 40 nautical miles (nm) above the Earth's surface) can attenuate, totally absorb, reflect, change direction of propagation, and change the phase and amplitude ...

Recent outer-heliosphere observations are reviewed from a space weather point of view by comparing the nature of solar wind, solar particle, and cosmic ray variations at the Voyagers and 1 AU. While the Sun still controls the interplanetary medium at 75 AU, the nearby boundaries of the heliosphere exert a strong influence on the environment.

The basic physics underpinning space weather is reviewed, beginning with a brief overview of the main causes of variability in the near-Earth space environment. Although many plasma phenomena contribute to space weather, one of the most important is magnetic reconnection, and recent cutting edge research in this field is reviewed. We then place this research in context by discussing a number of...

Space weather describes the way in which the Sun, and conditions in space more generally, impact human activity and technology both in space and on the ground. It is now well understood that space weather represents a significant threat to infrastructure resilience, and is a source of risk that is wide-ranging in its impact and the pathways by which this impact may occur. Although space weather...