ICG-5 WG-B, Turino Ionospheric Monitoring in China Zhen Weimin, Ou Ming October 20 th, 2010, Turino, Italy
Outline 1.Introduction 2.Ionosphere monitoring in China 3.Summary
1. Introduction GNSS performance is influenced by the ionosphere, its monitoring is quite important for the system performance. There exist many ionospheric monitoring network in some countries, like USA, Russian, Japan and European area. The Ionospheric monitoring network could be used for many different applications.
Chinese Ionosphere Monitoring Network Global Ionospheric Modeling Regional Ionospheric Modeling 2. Ionosphere Monitoring in China Ionospheric Physics Regional precise ionospheric correction models New technologies application in ionosphere detection Ionospheric threat models for SBAS Ionospheric Disturbance Effects on GNSS
2.1 Chinese Ionosphere Monitoring network Ionospheric monitoring network Cover most of the subcontinent. Real time monitoring. Monitoring methods: GPS- for TEC and Scintillation. Tri-band satellite beacons Ionosondes Oblique sounders VLF device Radar.. Ionosphere monitoring network in China Earthquakes monitoring network in China GNSS-based ionospheric Scintillation monitoring network in China
Ionosonde Antenna of Ionosonde Ionospheric scintillation monitor with GPS
2.2 Global Ionospheric Modeling A correction model Chinese Reference Ionosphere (CRI) is developed; Middle and low latitude theoretical Ionospheric model-theoretical Ionospheric Model of the Earth in Institute of Geology and Geophysics, Chinese Academy of Sciences (TIME-IGGCAS); Ionospheric TEC comparison between CRI,IRI and observations Ionospheric Electron Density by TIME-IGGCAS
Ionospheric Modeling for GNSS Based on CRI and NeQuick model, a modified model is under development to satisfying GNSS use Ionospheric Eclipse Factor Method for Single-frequency GNSS User Modified Klobuchar Model for China Regional GNSS Error distribution of the original model Error distribution of modified model (IRI) Performance comparison between the original model and the modified model for GNSS
2.3 Regional Ionospheric Model a) Ionospheric Physics Long-term trends of the ionosphere variations; Ionospheric disturbances studies; Characters of ionospheric scintillations in low-latitude area of China; Character of ionosphere in polar region. Ray Tracing through the ionosphere 600 12 500 10 400 8 Height[km] 300 6 200 4 100 2 Ionospheric long-term forecasting(fof2) 0-2000 -1500-1000 -500 0 500 1000 1500 Ground Distance [km] Ray tracing for ionospheric disturbances detection 0 Ionospheric scintillations
b) Regional precise Ionospheric correction models Spatial and temporal correlation studies conducted to look for a better way for ionospheric TEC map reconstruction and prediction. The presented TEC mapping system has been used for estimate the ionospheric TEC over China. Realization of a suitable regional ionospheric model for augmentation system. Ionospheric TEC mapping with Kriging technique Ionospheric TEC forecasting with autocorrelation method (Black: measured TEC; Red: Forecasted TEC; Blue: Error of forecasted TEC )
c) New technologies in the ionosphere detection CIT, Computerized Ionospheric Tomography, used for fine Ionospheric parameters reconstruction. GNSS occultation for global Ionospheric weather research. CIT for GNSS Augmentation application. Ground based ionospheric tomography GNSS occultation in the global ionospheric NmF2 detection CIT for geomagnetic storm imaging
2.4 Ionospheric threat models for SBAS A Ionospheric threat model has been developed to overbound the ionospheric delay errors. Thus the performance of ionosphere related integrity is improved. 12 Vertical Ionosphere Decorrelation (China 17th Mar.09) x 10 4 4.5 Residual Ionosphere Difference Probability (China, 17th Mar. 09) Residual Ionospehre Containment σ (China 17th Mar. 2009) Δ I (m) 11 10 9 8 7 6 5 4 3 2 1 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 dist(km) 4 3.5 3 2.5 2 1.5 1 0.5 probality of exceeding dion. 10-1 10-2 1 2 3 4 5 6 7 8 9 10 11 delta iono. delay between IPPs σ bound(m) 12 11 10 9 8 7 6 5 4 3 2 1 68% 95% 99% 99.9% 0 0 500 1000 1500 2000 2500 3000 distance between IPPs Research of Regional Ionospheric Characters in China
2.5 Ionospheric Disturbance Effects on GNSS Ionospheric scintillation monitoring and forecasting in low-latitude areas in China. Impacts analysis of ionospheric scintillation on the GNSS. Signal fading L1 C/No (db) L2 C/No (db) C/N0 fluctuating 75 m50 m25 m Ionosphere scintillation distribution over China. (made by CRIRP) Positioning error Tracking error S 4 Ionosphere scintillation impacts on GPS positioning
2.6 Improvements for GNSS in China Ionospheric scintillation model Studies are carried out on ionospheric scintillation model which could be used to current and shortterm forecasting in China sub-continent. Ionospheric models for GNSS Regional Augmentation system New single frequency correction algorithms Ionospheric threat models Detecting methods for ionospheric irregularity
2.7 Further Works Global Ionospheric Modernization Models optimization for GNSS Improvement of Ionospheric threat models for SBAS New technologies application in the SBAS Ionospheric correction modeling, for example, the Computerize Ionospheric Tomography, GNSS occultation, etc. Satellit e vox el Receiv er Multi-layer Ionospher e The Earth Computerize Ionospheric Tomography GNSS occultation
3. Summary Ionospheric is quite important for GNSS applications China has established an Ionosphere monitoring network and provide data for GNSS service The current monitoring network could be updated and expanded on demand China is open for the international cooperation in this area.
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