GNSS application for space weather operation in Taiwan

At the lower latitude region, the electron density distribution significantly influences high-frequency and satellite communication as well as navigation and positioning services. Over Taiwan, there is a high density of plasma during the day which is associated with the equatorial ionization anomaly, and plasma bubbles/irregularities appear in the evening to midnight period. In order to monitor the variation of ionospheric electron density and the movement of ionospheric irregularities, the Space Weather Operational Office of Central Weather Administration (CWA/SWOO) has collaborated with Taiwan Space Agency (TASA) and domestic scientific research teams from universities to establish various products which by applying the Global Navigation Satellite System (GNSS) signal. By using ground-based and space-based observations, CWA/SWOO provides real-time global and regional total electron content (TEC), scintillation index, rate of TEC index, as well as ionospheric radio occultation profile, etc. Meanwhile, a Global Ionospheric Specification and an ionosphere-thermosphere coupled assimilation system is operated by combining GNSS observations to reproduce three-dimensional electron density structure and short period forecast of ionosphere and thermosphere, respectively. In addition, in order to understand the relationship between positioning error and ionospheric features, CWA/SWOO also conducted a system to monitor positioning of a few reference stations around Taiwan in real-time. It would provide a good dataset to make comparisons of positioning error and irregularities.