Determining accurate regional geoid with Stokes theory can be affected by gravity data errors, such as resolution of gravity, precision of mean gravity and integral radius. In order to solve this problem, the magnitude of truncation errors of geoids in different terrain areas, which are caused by gravity resolution and integral radius, are given based on the analysis of characteristics of the gravity frequency spectrum. Also, the effect of error of mean gravity anomalies on geoid construction is calculated. Therefore, the results put forward in this paper contain great theoretical value for centimeter geiod calculation in different terrain areas.

In this paper, the performance of zero velocity update (ZUPT) in the GNSS/INS tightly coupled integration is researched. First, we propose a zero velocity judgment method by the utilization of GNSS/INS tightly coupled solver velocity solutions, IMU raw data and doppler data. Then, the mathematical model for the ZUPT added GNSS/INS tightly coupled integration is introduced in detail, and it is verified by vehicle testing. The statistics show that the new zero velocity judgment method is very effective in detecting the static state of the platform in comparison with real situations. By using this ZUPT mode, the IMU sensor error accumulation while stationary can be constrained visibly, especially in poor observation environmental conditions. Compared to the result without ZUPT, in a short time in the stationary state, the carrier position and velocity accuracy can be improved by 27% and 35% respectively in the quality of satellite observations, and 16%-75% and 87%-97% respectively in the case of 30-120 s satellite signal interruption. However, the improvements of altitude accuracy are not obvious whether the satellite signal is normal or interrupted when the stationary time is not so long.

The gravity Bouguer anomaly values in Alxa Left Banner MS5.8 epicenter and surrounding regions of Inner-Mongolia (105°-110°E,36°-41°N) are obtained using the FA2Boug algorithm with EGM2008 free-air gravity anomaly and DEM data. The results show that the epicenter locates at the high gradient brand of the gravity Bouguer anomaly, and there exists different forces inside the Erdos block.

Wave and wind effect marine magnetic survey data in the vertical space.  This is because the two-dimensional Taylor polynomial doesn’t include the influence of the change of height in establishing the regional marine geomagnetic field model. In order to solve this problem, a three-dimensional Taylor polynomial is put forward to construct the regional marine geomagnetic field model. By simulating a certain area of underwater sphere magnetic field and ship-borne magnetic survey data, this paper analyzes choosing the truncation order of the two models, the difference between the complete polynomial expansion and the classical expansion methods, and the boundary effect of the two methods. The results show that: the three-dimensional Taylor polynomial method can reflect the distribution of marine magnetic anomalies better and overcomes the boundary effects in considering the height changes.

The orbits of altimetry satellites should be repeat groundtrack and frozen. We derive an algorithm of the orbit design based on zonal geopotential field and develop the software by ourselves. This paper takes ICESat and HY-2A as examples, computing their mean orbit elements and osculation orbit elements. The orbit generation results show that the satellites can get a nice closure after a full cycle and there is no secular and long period change for the semi-major, eccentricity, inclination and the argument of perigee. The orbit can meet the requirement of altimetry satellites and can be taken as a reference orbit.

We discuss the method of orbit determination combining the on-board data of LEO with the observation data of regional monitor stations. In order to validate this proposed approach and its performance, the observation data of 7 GPS stations in China and on-board data of GRACE-A&B during March 16-31, 2011 are collected and orbit determination experiments were carried out. The results show that, compared with the result of 7 stations, the visibility of GPS satellites is increased by about 14%. Meanwhile, the precision of GPS orbits expressed in R,T,N components are improved by about 35%, 44% and 45% respectively when introducing only GRACE-B; improvements in R,T,N components of 51%, 60% and 62% are achieved when both GRACE-A and GRACE-B are introduced and the visibility of GPS satellites is increased by 18% in this case. The proposed approach provides a new means to improve the orbit determination accuracy of navigation satellites under the restriction of regional monitoring stations.

This paper discusses the scheme for analyzing the error of BDS broadcast ephemeris. By contrasting with IGS MGEX’s precise ephemeris and clock products, this paper presents statistics of orbit and clock error of broadcast ephemeris of all in-orbit BDS satellites for a period of 31 d. The results show that: 1)The RMS of radial orbit error of current BDS broadcast ephemeris is less than 1 m, tangential and normal RMS is less than 8 m for GEO satellites, and tangential and normal RMS is less than 4 m for IGSO and MEO satellites. 2)The RMS of BDS clock bias error has no relationship with orbit types and is less than 15 ns. 3)From the perspective of signal-in-space range error, the relationship of the overall accuracy of BDS satellites broadcast ephemeris and orbit type is not clear and the overall accuracy is less than 2 m.

In order to study the characteristics of BDS carrier phase multipath, the BDS/GPS observation data of a short baseline is collected in a strong multipath environment and the repeatability of GEO, IGSO and MEO satellites are analyzed respectively using the double differenced observation residual series. Furthermore, the effects of BDS multipath on static baseline solutions are studied. The results show that BDS multipath errors have a strong repeatability, but the multipath repeat periods differ for distinctive types of satellite. The multipath repeat periods of GEO and IGSO satellites are approximately a sidereal day, while it is around seven sidereal days for the MEO satellites. The multipath errors of GEO satellites present a nearly systematic shift; not a constant, but slow, change. They cannot be mitigated by smoothing using long observation time, because the effects of BDS multipath errors on static baseline solutions could reach the centimeter level in a strong multipath environment.

This paper first analyzed the data interruptions of RTS (real time service） products, and second carries on research into methods of repairing of these disruptions. According to statistics on the interval distribution of these data interruptions, the maximal repairable interval of 15 min is selected. Then, the data interruptions less than 15 min are repaired with different interpolation methods. The satellite orbit data interruptions are repaired using the common Lagrange interpolation with different orders. In order to explore the optimal solution, the satellite clock data interruptions are repaired with the Lagrange interpolation, cubic spline interpolation, linear interpolation and linear fitting, respectively. Finally, an experiment of simulative near real-time PPP on the IGS station is conducted using the repaired RTS orbit and clock products to verify the proposed method.

Based on data collected for six days at fifteen stations of Hong Kong satellite positioning reference station network (SatRef) in 2014, we combine GPS and GLONASS to perform a three-dimensional water vapor tomography experiment. The results show that the integrated GPS/GLONASS system can significantly increase the number of voxels which are passed through by the signals. The system improves the accuracy of distribution of water vapor by an average improvement rate of 36% in comparison with a GPS-only system.

Currently GNSS observation data for quality evaluation is based on multipath, data integrity, cycle slips and SNR. In this paper, the factor of data efficiency is increased to assess data quality. The method of multi-index comprehensive evaluation firstly proposed is applied to evaluate GPS data quality based on GPS observations from iGMAS, MGEX and IGS. A comprehensive evaluation model is developed based on TOPSIS. Pearson correlation analysis is conducted between the results of the comprehensive evaluation model and various data quality indicators, showing that a strong correlation exists between the results of comprehensive evaluation and data integrity as well as data efficiency. The results of correlation analysis between static PPP results and the comprehensive evaluation show a significant correlation.

The 40 m caliber radio telescope, at the Haoping station of the National Time Service Center, is crucial to satellite monitoring and maintenance work, but there is limited research on how to accurately measure the phase center reference point coordinates. Aiming at this problem, this article introduces the measurement solution of phase center reference point coordinates, including GPS control net setting, observation and data processing, the measurement of the rotation center’s coordinate and curve fitting, and the coordinate transformation of rotation center to reference point. The results of the precision analysis show that the accuracy of reference points is better than 8 mm in the CGCS2000 coordinate system.

ERP is a necessary parameter in the transformation between the ITRF and ICRS. The paper introduces a method of solving the ERP parameters based on GPS data. First, about 100 global uniform and stable distributed IGS stations are selected for the calculation of the solution, and then we make comparisons between the solution sequence from the experiment and the IGS final-solution sequence. Second, we analyze the impact factor of the solution quality from the aspect of experimental data and mathematical derivation during processing, including the constraints for the orbit, the precision of the prior ERP information, and the quantity of the chosen station. We then make a proposal for improving the ERP solution quality based on the analysis: freely constrain the four periodic dynamic parameters in the directions D, Y of ECOM model, and the strongly constrained stochastic pulse can achieve a better result. The key to reducing the influence of the prior information in the processing is to improve the precision of predicted UT1-UTC; 100 stations in the processing is a good choice to achieve the best efficiency and quality in the calculation.

Using digital waveform data recorded by region seismic networks along with relevant seismic phase data collected by the China seismograph network, we calculate the attenuation characteristics and site response for the Panzhihua-Xichang area. The frequency dependent Q(f) is obtained by the iterative grid-search technique described by Atkinson and Mereu, based on a trilinear geometrical spreading model. The source spectra is determined by the model of Brune and the site responses of seismic stations derived by Moya’s method, which uses genetic algorithms. Our results demonstrate that the associated model for the regional quality factor for frequencies can be expressed as Q(f)=944f0.665 9 (from May, 2008 to December, 2013）and Q(f)=83.9f0.719 6 (from January, 2014 to June, 2015）for the Panzhihua-Xichang area. Site response results indicate that different stations show different amplifications.  Site amplifications in the Panzhihua-Xichang area are between 1.13 and 6.93 times. For tectonically stable cratonic regions, the Q0 is usually high; in contrast, for tectonically active regions, such as the Panzhihua-Xichang area, the Q0 is generally low. Broken media caused by strong tectonic activity or upper-mantle heterogeneity and velocity structure may be the main reasons of low Q0 values in this area.

In this paper, we use ambient noise tomography to study the Shanxi regional crustal velocity structure and deep tectonics.The data includes 7 months (2014 January to 2014 July) three-component continuous data recorded at 44 seismic stations of Shanxi province digital seismic networks and its surrounding . The S-wave velocity structure of the crust is inverted from Rayleigh wave dispersion maps. The S-wave velocity maps show clear lateral variations that correlate well with major geological structures and tectonic units in the study regions: in the upper crust, S-wave velocities of the Shanxi fault depression zone are relatively low at shallow depth, while the uplifts on sides of Shanxi fault depression zone show high velocity. In the mid-lower crust, the latitude ~38.5°N divides the region into a northern part with a low velocity anomaly and a southern part with a high velocity anomaly. Datong basin shows low velocity in the crust,possibly related to the wide distribution of volcanoes.

The 1966 Xingtai earthquake devastated densely populated areas. There were a total of five MS≥6.0 earthquakes in 21 days. Many studies have shown that there was intense magmatism under the area. Analysis of the static Coulomb stress triggering of the five earthquakes shows that the triggering of the first two earthquakes had good relations, but that the relations after the MS7.2 earthquake triggering were not ideal. This paper argues that, as the earthquakes occurred, the focal depth increases, the impact on the crust magmatism grows, and the elastic properties of crustal medium weakens. The shallow part of the region can be approximated with homogeneous elastic half-space. However, for the deeper part, under the influence of magma and other factors, there is a big error in calculation of earthquake triggering with homogeneous elastic half-space. This is not suitable for calculating the earthquake triggered by the elastic dislocation theory. Furthermore, this also reflects the regional magmatic activity and the objectivity of the existence of the super crust fault.

In this study, we calculate GPS observation data from 76 continuous sites between May 2011 and June 2013 of the CMONOC and HBCORS networks. We get the precise coordinates, the time series, and the horizontal movement velocity field of each station. The results show that the movement speed is about 6-9 mm/a, and gives priority to movement to the east or southeast direction, which is almost the same as the movement characteristics of the south China block. The preliminary results show that there is no obvious difference in the Hubei region. Also, we calculate the principal strain rate and the maximum shear strain rate. The results show that the maximum shear strain rate sensitive area is mainly the area where the faults distribute centrally; the maximum value mainly distributes in Badong, Zigui and Zhushan-Yunxian and its neighbor area; the value is about (1.43-1.73)×10-7/a, ,the results correspond obviously to Zigui M4.5 and M4.7 earthquakes, and Fangxian M4.0 earthquake in Hubei region in 2014.

A SVM model is established for predicting dam deformation, and optimizing the kernel function parameter, penalty parameter and loss function parameter through the genetic algorithm. We use this model to analyze the long period deformation monitoring data and make predications. In this paper, we compare horizontally different kernel functions of support vector machine using the same optimization method, and the same kernel function of support vector machine using different optimization methods. The results show that GA-SVM(RBF) not only can well predict the dam deformation trend, but also improves the prediction accuracy over contrasting BP neural networks, AR(p), multiple regression analysis and periodic function fitting longitudinally.

Selecting different period data of Wushi body strain and air pressure, we apply wavelet analysis method to separate observation data signals, using correlation analysis of body strain and air pressure in the same frequency band. The results show that the effect of air pressure on body strain is mainly expressed as a linear relationship, and that there are two outstanding bands.

The interrelation analysis is used in the daily mean values of 2013-2014 bore-hole body strain and underground water from Hefei and Huangshan seismic station. Considering the body strain change lagged the change of water level,this article uses the cross correlation coefficient analysis.Determine the maximum correlation coefficient appeared in the number of days .Through analysis the regression fitting to eliminate underwater interference.The results reflect the real variation of bore-hole to extract seismic anomaly purpose.

This paper is concerned with distinguishing rainfall disturbance from tectonic deformation. We use an in-phase stack technique on crustal deformation data and corresponding rainfall data in Kunming and Yunlong stations to judge whether the patterns repeated in crustal deformation data are related with rainfall. We argue that the patterns in Kunming station support rainfall disturbance but that the patterns in Yunlong station do not.