A Statistical Study of the Ionospheric Anomalies Affecting SBAS Safety Detected over China Area in 2015

Abstract

Ionospheric anomaly is the greatest risk affecting the integrity of the Satellite-Based Augmentation System (SBAS). The frequent occurrence of ionospheric anomalies in the low latitude area of China will degrade the accuracy of SBAS grid models severely. Moreover, it will influence Single-frequency SBAS service performance and threaten the safety of aviation users. In 2020, the Beidou global navigation system will be fully completed. For the safety problem of the BeiDou Satellite-Based Augmentation System (BDSBAS) caused by the ionospheric anomaly, it is necessary to carry out statistical research on the SBAS ionospheric anomaly in China. Based on a large volume of observation data from the Crustal Movement Observation Network of China (CMONOC). For the first time, this paper conducts long-term and large-scale research on the nature of SBAS ionospheric anomaly events as type, impact area and occurrence time over China area in 2015, which was the most active year for geomagnetic activity in the 24th solar cycle. In addition, solar activity is strong in 2015. The research shows that apart from the SBAS ionospheric anomaly events caused by Equatorial Ionization Anomaly (EIA), there are the SBAS ionospheric anomaly events caused by the Regional Ionospheric Disturbance (RID). Both happen frequently in China, and the area and time are relatively regular, which can be regarded as “daily anomaly”. It is greatly affected by solar activity and has the characteristics of obvious seasonal variation. The occurrence frequency and activity intensity are high in Spring and Autumn, but low in Summer and Winter. The impact of the ionospheric storm on SABS is random and sporadic. There is no SBAS ionospheric anomaly event caused by typical mid-latitude ionospheric storms in the data of 2015. It mainly affects the EIA over China area, which can be regarded as “abnormal anomaly”. The results of this study will provide data support for the research studies of the integrity of the ionospheric anomaly during the construction of the BDSBAS in China.