Real-time ionospheric science: The new reality

Until the early 1990s, near-real-time updates to monthly climatological ionospheric models were driven primarily by military requirements. Since then, civilian research and commercial requirements for corrections to precise satellite ranging systems have become the driving forces for real-time ionospheric data, and they likely will continue to be major reasons for the a availability of worldwide transionospheric observations in the future. This paper outlines the development of some of these requirements and describes the likely future availability of ionospheric observations for near-real-time updating of ionospheric monthly climatology.