| As an important component of the solar terrestrial space environment,the ionosphere is one of the key links that affect human activities.On the one hand,the ionosphere has an important impact on wireless communication,navigation positioning,and human space activities.On the other hand,ionosphere has a wide range of application scenarios in space disaster weather monitoring and natural disaster monitoring.With the development of global navigation satellite systems(GNSS),satellite-based and ground-based GNSS monitoring,inversion,and research on the ionosphere can improve human understanding of the formation and related activity mechanisms of the ionosphere,understand and master the spatiotemporal changes of the ionosphere,which have important scientific value and practical significance.The time-space resolution of the ionosphere monitored by the traditional ionospheric detection technologies is limited,and they will also be affected by natural weather conditions.Moreover,their cost is expensive and they can not achieve a high global coverage,so it is not easy to obtain the global ionospheric attribute parameters.Moreover,the resolution of the ionospheric electron density obtained in the vertical direction is low,and they can not accurately detect and reflect many thin or special ionospheric structures.The satellite based GNSS occultation inversion technology and the ground based GNSS receiver receiving satellite signal correlation processing technology can solve these problems to a certain extent.This paper focuses on combining the satellite-based and ground-based GNSS ionospheric modeling and monitoring research,focusing on the breakthrough of electron density profile inversion and sounding Es that take into account the characteristics of the ionospheric detection data of China Seismo Electromagnetic Satellite(CSES),and realizing the GNSS ionospheric monitoring inversion and application in space disaster weather monitoring and natural disaster monitoring.The main work and conclusions are as follows:(1)The application of GNSS occultation in ionospheric inversion is mainly introduced in conjunction with CSES.Considering the quality of CSES observation data,data quality evaluation and analysis are conducted on the GNSS occultation receiver of CSES in terms of daily observation occultation number,signal-to-noise ratio,inter epoch cubic difference,and MP combination for nearly one year of observation data.The results showed that at the beginning of signal acquisition,the GNSS occultation receiver received both P1 and P2 observations from GPS satellites,which were affected by abnormal jumps,particularly P2.The data quality of BDS-2observations received by CSES was much better than that of GPS.In this field,a quality control algorithm based on MP combination is proposed for the first time to apply CSES data quality control and occultation inversion.Research shows that the algorithm can effectively detect and remove outlier of electron density profile during occultation inversion.(2)In view of the demonstration of the accuracy and reliability of CSES occultation inversion of ionospheric electron density,this paper uses the peak density and peak height extracted by CSES and COSMIC(06),and compares them under different space–time matching criteria.The experimental results show that the correlation coefficients between the GPS satellite observed by CSES with four different space–time matching criteria and the peak density of COSMIC(06)are 0.943,0.948,0.945,and 0.959,respectively.The correlation coefficients for the peak height are 0.794,0.801,0.801,and 0.833,respectively.The results show that there is a significant correlation between the electron density profiles obtained by CSES and COSMIC(06)observation satellites.(3)Different from the traditional occultation detection sporadic E-layer(Es)algorithm,this paper implements a new threshold judgment criterion and algorithm to determine the Es events based on the characteristics of CSES observations,that is,Es occurs when the mean value of the absolute value of the difference between the normalized SNR is greater than 3 times the standard deviation.This algorithm has the advantage of without loss of generality.Combined with the electron density profile of occultation inversion,the correctness of our Es sounding algorithm is verified.Based on the detection results,this article has completed a discussion on the global distribution of Es.Finally,by comparing the results of sounding Es with ionosonde,the differences in height parameters used by the two technologies were studied,and the correlation coefficients of the heights detected by the two technologies were calculated.The results also verified the feasibility and reliability of the Es detection algorithm.(4)This article combines the satellite-based and ground-based ionospheric monitoring inversion module based on the GNSS distributed high-precision data processing platform FUSING,and applies it to ionospheric disturbance monitoring during geomagnetic storms and volcanoes.This article takes the August 2018 geomagnetic storm event as an example to conduct occultation inversion monitoring and three-dimensional ionospheric tomography monitoring using joint ground-based GNSS Quasi-4-Dimension Ionospheric Modeling(Q4DIM)to verify the impact of geomagnetic storms on ionospheric disturbances.Taking the Tonga volcanic event in January 2022 as an example,the monitoring of ionospheric stratification structure by occultation and the analysis of ionospheric scintillation were conducted.The results showed the gradual response and state changes of the ionosphere before and after the volcanic eruption. |
