The ionosphere, the upper atmosphere between 60 and 1,000 kilometers above the Earth's surface, is the focus of space weather applications because of its large number of free electrons, which can have a significant effect on radio signals passing through or reflected in it. GNSS (Global Navigation Satellite Systems), represented by China's Beidou, US GPS and EU Galileo, can not only provide users with high-precision navigation, positioning and timing services, but also serve as a remote sensing system for space radio signals. It can also conduct detailed exploration of the space atmosphere.
Schematic diagram of the hierarchical structure of the Earth's atmosphere
The relationship between the Global Navigation Satellite System and the ionosphere
Beidou /GNSS navigation signals are sent from satellites more than 20,000 kilometers from the Earth, pass through the Earth's atmosphere (mainly including the ionosphere and troposphere), and are received by receivers mounted on the Earth's surface, near space or low-orbit satellites. By accurately measuring the atmospheric delay, power attenuation and amplitude change of navigation signals, the parameters of atmospheric temperature, pressure, humidity and electron density along the signal propagation path can be retrieved, and each receiver and each visual satellite can form a group of effective observations.
Space atmosphere observation diagram based on Beidou /GNSS
GNSS is considered to be the only detection means with high accuracy, good continuity, global coverage and low cost, which can complement the advantages of traditional observation means. In particular, with the increasing number of space satellite constellations and ground monitoring stations, the observation accuracy, time and spatial resolution will be further improved. High-precision ionospheric monitoring and inversion based on GNSS is not only conducive to promoting ionospheric physics research and solar-Earth space weather applications, but also plays an important role in improving the navigation, positioning and timing service performance of Beidou /GNSS.
Schematic diagram of the space ionosphere in relation to our everyday lives
The GNSS Ionospheric Research Team (GIPP/AIR) of the Department of Navigation Systems, Institute of Aerospace Information, Chinese Academy of Sciences, led by Dr. Zishen Li, has long been committed to fully exploiting and exploiting the characteristics and advantages of multi-mode and multi-frequency signals such as Beidou /GNSS, and realizing accurate monitoring and inversion of key parameters of global/regional/local ionospheric weather. It has developed space ionospheric monitoring equipment and Service system based on Beidou /GNSS, and jointly built IGS (International GNSS Service) ionospheric Analysis Center, code-named CAS. Among them, GIPP/AIR team members mainly include: Ningbo Wang, Liang Wang, Kai Zhou, Wen Li,Ang Liu, etc.
GNSS ionospheric research team mainly studied schematic ideas
Jointly undertake the construction of IGS Ionospheric Analysis Center (code-named CAS)
A Beidou /GNSS space atmospheric Monitoring receiver -- BDSmart (BDS/GNSS ionospheric Monitoring And Retrieval Terminal) -- Based on real-time products of high precision satellite orbits, clock and difference code errors, The real-time monitoring of ionospheric scintillation, TEC, perturbation and atmospheric precipitable water can be realized at a single reference station, which greatly reduces the data processing burden of the center and improves the monitoring efficiency, laying a foundation for the large-scale construction of the Beidou /GNSS atmospheric and ionospheric observation network in China.
Developed Beidou /GNSS Space Atmosphere Monitoring Receiver (BDSmart)
A cloud-based Beidou /GNSS ionospheric data processing and service system has been built, using the observation data of GNSS reference stations distributed globally/regionally. Support global/regional/local ionospheric TEC real-time and post-hoc accurate monitoring and modeling, global/regional/local ionospheric disturbance monitoring and calculation, accurate estimation of difference code deviation of multi-mode and multi-frequency navigation satellite system, global broadcast ionospheric delay correction model refinement of Beidou /GPS/Galileo, global/regional/local ionospheric real-time product broadcast service Service and other functions.
Operation status of the Beidou /GNSS ionospheric data processing and service system based on the cloud platform
It realized the business processing of final, fast, forecast and real-time products of Beidou /GNSS global ionospheric TEC grid, and routinely submitted to IGS product Center.
Performance comparison of global IGS ionospheric analysis Center products during the last two solar cycles
Global ionospheric real-time product services provided by CAS Ionospheric Analysis Center
It took the lead in realizing unified definition and accurate estimation of multi-mode and multi-frequency GNSS code deviation (DSB and OSB parameters) for Beidou, GPS, Galileo, GLONASS and QZSS. Related products were routinely submitted to IGS and released to the public.
The exact estimation result of difference code deviation of our Beidou Global System (BDS-2/3)
Routine Accurate Estimation Results of OSB Parameters in Multi-frequency and Multi-mode GNSS (Taking GPS as an Example)
The real-time refinement service of Global navigation satellite system broadcast ionospheric delay correction model was carried out, and Klobuchar (GPS), BDGIM (BDS-3) and NeQuickG (Galileo) correction parameters were released to the public.
Klobuchar (GPS) and NeQuick (Galileo) parameters after CAS refinement were compared with the original model
Beidou Broadcast ionospheric delay model after CAS refinement -BDGIM
To actively promote the study of global/regional/local ionospheric disturbance monitoring based on Beidou /GNSS, and provide support for real-time accurate monitoring and early warning services of ionospheric anomalies.
Global ionospheric ROTI products provided by CAS Ionospheric Analysis Center
It has been successfully applied to the mass intelligent terminal, and integrated Beidou /GNSS real-time satellite orbit, clock difference, difference code deviation and ionospheric real-time products, which can assist mobile phones to realize sub-meter navigation and positioning services.
Volkswagen smartphone uses global real-time ionospheric, orbital and clock difference products before and after positioning effect comparison
GNSS ionospheric data product server is built for interested users to download related products, carry out services and research.
ftp address: ftp.gipp.org.cn
CAS Ionospheric data Product server directory structure