Evaluation the quality of FORMOSAT-7/COSMIC-2 Observation Data and its application for ionospheric monitoring during the extreme space weather

Owing to the advantages of high vertical resolution, global coverage, high precision, and all-weather operation, GNSS occultation has been widely used for ionospheric weather monitoring and meteorological forecast. Aiming to obtain the meteorological, climatic, and ionospheric information, FORMOSAT-7/COSMIC-2, the successor constellation of COSMIC-1, is jointly launched by the United States and Taiwan on June 25, 2019. As a new generation occultation constellation, COSMIC-2 consists of six low-latitude satellites with an orbital inclination of 24 degrees and an altitude of 520km. In contrast, COSMIC1 consists of the high-latitude satellites with an orbital inclination of 72 degrees and an orbital altitude of 720km. These differences in constellation structure, orbital altitude, and inclination inevitably lead to the difference in observation quality.

 

Firstly, in this contribution, the qualities of satellite-based GNSS observations from COSMIC-2 and COSMIC-1 are both analyzed and compared. The result shows that the satellite-based observation data of COSMIC-2 are improved significantly compared with COSMIC-1. The multipath effect reduced by more than 40%, and the probability of cycle slip decreased by three times. Then the occultation observations of the two constellations are also analyzed. Next, using the observations of COSMIC-2 satellites in 2020, an ionospheric total electron content (TEC) model was established. Finally, the TEC model was adopted for investigating the ionospheric disturbances under extreme space weather in 2020.

 

Keywords: COSMIC-2; Ionospheric TEC Model; Extreme Space Weather