By comparing the differences between various drift models and adjustment methods through simulated gravity data adjustment, certain optimizations were made to the gravity adjustment algorithm. Methods for multiple segment difference adjustment and constrained linear programming adjustment were proposed. The results indicate that the multiple segment adjustment method outperforms other adjustment methods in some aspects, while the constrained linear programming adjustment method demonstrates overall superiority over other adjustment methods.

A multipath error mitigation method suitable for dynamic landslide deformation monitoring points is proposed. This method replaces the fixed position parameters used in the residual extraction process with dynamic displacement parameters that reflect actual deformation to eliminate systematic errors caused by deformation. The method employs sidereal filtering(SF) and multipath hemispherical mapping(MHM) to mitigate multipath effects in dynamic landslide scenarios. Experimental results show that the proposed multipath mitigation method based on dynamic displacement parameters can be effectively applied to dynamic deformation monitoring scenarios. Compared with the original unfiltered results, during the constant velocity deformation stage of the landslide, the positioning accuracy in the east direction is improved by 13% and 27%, in the north direction by 15% and 30%, and in the height direction by 11% and 22% for SF and MHM based on dynamic displacement parameters. During the accelerated deformation stage of the landslide, the positioning accuracy in the east direction is improved by 12% and 24%, in the north direction by 23% and 32%, and in the height direction by 5% and 19% for SF and MHM based on dynamic displacement parameters.

To address the issues of abnormal and non-smooth fitting results in sparse monitoring station areas and block margins when using the traditional least squares collocation (TLSC) algorithm for high-precision fitting of crustal motion velocity fields in large-scale regions, a K-means clustering-based least squares collocation method (KLSC) is developed by integrating the K-means clustering algorithm with the TLSC algorithm. The effectiveness of this method is validated using the GNSS-measured crustal motion velocity field on the Qinghai-Xizang plateau. The results show that: 1) Compared to the TLSC algorithm, the KLSC algorithm leverages the advantages of the K-means algorithm in unsupervised classification to first divide the study area into multiple sub-regions with similar velocities based on the inherent characteristics of the GNSS velocity field, and then applies TLSC for velocity field fitting within each sub-region, thereby avoiding the impact of local complex geological environments on the accuracy of regional velocity field fitting; 2) The KLSC algorithm selects fitting parameters based on the proximity of each grid point to the cluster centers, resolving the issue of poor fitting results in data-sparse areas; 3) By utilizing secondary nearest-neighbor fitting combined with convolution filtering, the KLSC algorithm effectively addresses the non-smooth fitting results at block margins; 4) The RMSE accuracy and correlation of the velocity fields fitted by the KLSC algorithm are superior to those of the TLSC algorithm, with improvements in RMSE accuracy of 37% to 48.2% and 52.1% to 67.2%, and increases in correlation of 24.1% to 24.7% and 4.7% to 5.2% for the eastward and northward fitted velocity fields, respectively.

We utilize long-term observation data from five superconductor gravimeters in China and Europe within the IGETS network, and apply various atmospheric pressure correction strategies to analyze the impact of time-varying admittance on the determination of Earth tide parameters. The results show that the temporal variability of admittance significantly influences Earth tide parameters, with effects on time-varying characteristics of the Earth's free core nutation period reaching up to 10 sidereal days. Taking into account the time-varying characteristics of admittance and global atmospheric pressure effects correction, the tidal wave amplitude factor is found to be closer to theoretical values. This has important implications for the construction of regional tidal models and subtle dynamic signals analysis.

We quantitatively analyzed the crustal strain changes in Xuzhou and Gaochun areas of Jiangsu province from 2019 to 2023 using four-component borehole strainmeters, and explored the characteristics of regional strain field and its relationship with seismic activity. According to the strain parameter results, both Xuzhou and Gaochun areas were in a stable state during the study period. The response values of tidal factors at Gaochun seismic station exhibited an abnormal change of first dispersion, then stabilization before and after the M5.0 earthquake in Dafeng sea area of Yancheng, Jiangsu province. Through the analysis of its variation characteristics, the relationship with the strike of faults and the focal mechanism solution of earthquakes, it can be inferred that in the process of earthquake preparation, the stress and strain in this area experienced a process from accumulation to release, and the tidal factors can reflect this change to a certain extent.

We investigate the deviation between IGRF13 model data and unmanned aerial vehicle(UAV) geomagnetic data in localized regions of China. By analyzing the differences in total geomagnetic field intensity, as well as the northward, eastward, vertical, and horizontal components of geomagnetic field between IGRF13 model data and aeromagnetic data in Weishui in Shaanxi province and Yuyao in Zhejiang province. The results show that the difference in total geomagnetic field intensity between IGRF13 model data and geomagnetic data in localized regions of China ranges from 100 to 200 nT. In the northwestern region of China, the difference is approximately 100 nT, while in the eastern coastal region, it is around 200 nT. After systematic calibration, the mean absolute error between the two datasets is less than 50 nT.

Using potential flow theory, we establish the Bernoulli hump, Kelvin wake, and internal wave models. Through simulation experiments, the impact of hydrodynamic wake produced by submarine on underwater gravity gradient navigation is quantitatively studied. The results show when the speed increases and depth decreases, the wake will generate significant disturbances in gravity gradient measurement. When the submarine travels at a depth of 40 m and a speed of 20 knots, the wake will produce gravity gradient disturbance on the order of 10^-9 s^-2, thereby affecting the accuracy of underwater gravity gradient navigation. In such cases, it is necessary to preprocess the measured signal to eliminate or reduce the impact of wake.

We use data from 9 CORS stations in Hong Kong from 2016 to 2021 to invert OTLD parameters, and evaluate the OTLD parameter inversion results based on the mean OTLD parameter values of EOT20, FES2014b, HAMTIDE11a, and TPXO9.2a ocean tide models. The results show that compared with GPS inversion results, the error of K₁, K₂, and S₂ tide components in multi-GNSS inversion can reduce by 15%-50%. In addition, comparing the changes of OTLD parameters in multi-GNSS inversion before and after mass loading correction, it can be seen that the improvement effect of OTLD parameters in vertical and east-west directions can reach 6.88% and 9.85%, respectively. However, due to the influence of internal interactions of mass loading, there is no significant improvement effect in north-south direction. Meanwhile, the improvement percentage of OTLD parameters in multi-GNSS inversion after mass loading correction is concentrated about 20%, which is positively correlated with OTLD.

We derive five spherical harmonic analysis algorithms in detail and develop a user-friendly and easy-to-operate practical software using the scientific computing language MATLAB. To validate the performance of five algorithms, we conduct a numerical analysis of the computational efficiency and accuracy of fast Fourier transform(FFT), least squares(LS), weighted least squares(WLS), approximate quadrature(AQ), and first Neumann method(FNM) algorithms at harmonic degrees of 180, 360, 720, 1 800 and 2 160, using the global topographic data DTM2006.0 as a case study. The results show that the AQ algorithm performs best in terms of computational efficiency, while the LS algorithm achieves the highest precision. The residuals of all five algorithms approximately follow a normal distribution, indicating that none of five algorithms exhibit systematic biases.

The seasonal microseismic signals at gravity stations are difficult to physically simulate and estimate due to the combined effects of randomness, intermittency, and periodicity. Based on the 1 Hz gravity solid tide data of Wushi continuous gravity observation station from 2008 to 2024, we extract the microseismic signals in DF frequency band using the apparent vertical displacement analysis method. An improved variational mode decomposition(IVMD) coupled with the long short-term memory(LSTM) neural network algorithm is proposed to establish a data model for seasonal gravity microseismic signals. The results show that the IVMD-LSTM model can better reflect the annual variation differences of seasonal signals compared to the LSTM model. Moreover, the correlation coefficient between model data using data-driven methods and the snow depth data from GLDAS and ERA5 models increased to 0.5. This study can provide a new processing method for model establishment using seasonal gravity microseismic signals and their application in earthquake analysis and forecasting.