*JANN-YENQ Liu1
(1.Center for Astronautical Physics and Engineering; Graduate Institute of Space Science, National Central University, Taiwan)
Keywords:ionospheric space weather, FORMOSAT-3/COSMIC, FORMOSAT-7/COSMIC, Kalman filter
The FORMOSAT-3 Project is also named Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC), or FORMOSAT-3/COSMIC (F3/C) for short. The project is targeted to place six micro-satellites into six different orbits with 72-deg inclination at 700~800 kilometer above the earth ground. These satellites orbit around the earth to form a low-earth-orbit constellation that conduct radio occultation (RO) by receiving signals transmitted by the 24 US GPS satellites. The satellite observation covers the entire global ionosphere, providing over 2,500 global RO sounding data (electron density and S4 scintillation profiles) per day since 15 April 2006. This for the first time allows scientists observing the 3D ionospheric electron density structure and dynamics. Simultaneous F3/C RO observations and ground-based receiver measurements of International GNSS (global navigation satellite system) Service (IGS) further initiate constructing three different models for monitoring (near real-time), nowcasting (few minutes to hours), and forecasting (few hours to days) the ionospheric weather resulted from the space weather (solar disturbances, solar winds, magnetic storms, etc.); the atmospheric severe weathers (typhoons, fronts, volcano eruptions, etc.); and the lithosphere weather (earthquakes, tsunami, etc.). The monitoring model is combining the total electron content (TEC) or the GNSS satellite signal scintillations of F3/C and ground-based IGS observations to construct an advanced GIM (global ionospheric map) to report the ionospheric bias and develop L-band scintillation models for communication, positioning, and navigation applications. The nowcast model is a global 3D ionospheric data assimilation model based on the Gauss-Markov Kalman filter with an existing background model to assimilate the TEC observations from the ground-based IGS receivers and space-based F3/C to output the global electron density for coming few minutes to hours. On the other hand, to carry out a long-term forecast, the neutral compositions in the atmosphere should be taken into consideration. Therefore, to develop a forecast model assimilating the observations of F3/C and IGS ground-based receivers into a neutral-ion coupled model. Following the F3/C, FORMOSAT-7/COSMIC (F7/C2) consists of six small-satellites with 24-deg inclination and about 500 km altitude will be launched in 2019. The developed models with F7/C2 RO by receiving signals transmitted by the GPS/GLONASS satellites and IVM (ionospheric velocity meter) plasma measurements as well as ground-based IGS GNSS data shall significantly improve the space weather monitoring/nowcast/forecast in the near future.