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Due to the characteristics of high accuracy and passivity, underwater matching navigation tech⁃ nology has become one of the main development directions of underwater vehicle navigation. To analyze the problems in gravity matching navigation, this paper introduces the development status of matching navigation based on gravity field products, and then discusses the constraints for positioning accuracy, including matching variables, gravity measurement precision, suitable matching areas and grid size. Gravity anomaly and gravity gradients of the two study regions are calculated by the spherical harmonic function based on a highly accurate gravity field model. And the influence of the grid size and the accuracy of gravity field product on the matching algorithm is evaluated. According to different kinds of indexes on gravity field charac⁃ teristics in the two study regions, it is easy to find that the study region of the South China Sea has much more abundant gravity field information and is more suitable for matching navigation than the Pacific Ocean. The gravity assisted matching navigation techno-logy is more suitable for use in the areas with obvious variations in gravity characteristics. If the grid size of the gravity field products is l, the highest precision of the matching navigation is 6l/6. [ABSTRACT FROM AUTHOR]

Objectives: It is important to determine the isostasy anomaly and the vertical tectonic stress for understanding the deep tectonic features and dynamics in Qinling area. At present, high-precision observation gravity data is one of the important means to obtain the isostasy anomaly and the vertical tectonic stress. Methods: The free-air gravity anomaly and the Bouguer gravity anomaly are computed by using gravity and GPS data, and the isostasy anomaly and the vertical tectonic stress are further inferred. Results: The results show that the isostasy depth is 40− 49 km, the Moho depth is 39− 48 km and the vertical tectonic stress carried by the crust is −28−24 MPa.Conclusions: The Weihe Basin on the northern of Qinling area is in a non-isostatic state. The isostasy anomaly and the vertical tectonic stress are approximately zero in the Northern Sichuan Basin, which indicates the basin is in an isostatic state. The local negative isostasy anomaly in Qinling indicates that there is existence crustal movement. [ABSTRACT FROM AUTHOR]

Objectives: In order to calculate the high precision gravity gradient in level 1b (L1b) data processing of gravity field and steady⁃state ocean circulation explorer（GOCE） satellite, it is necessary to accurately measure the satellite attitude angular velocity. In the coordinate system transformation of the attitude data of astrology, the low precision angular velocity components of a single astrology instrument will transmit the noise to other angular velocity components, which will affect the calculation accuracy of the whole gravity gradient.Methods: In this paper, based on the noise characteristics of the astrological instrument, the weighted matrix of the noise distribution on each axis of the astrological instrument is constructed, and the optimal attitude quaternion is solved jointly for the attitude quaternion of two or more astrological instruments, so as to provide accurate attitude control for subsequent angular velocity recovery. Results: Compared with the single astrometer calculation method, the accuracy of the optimal attitude angular velocity components wy and wz obtained by the combination of multiple astrometers can reach about 1 order of magnitude higher within 10-100 mHz, and the noise level is up to 10-6 rad/s， which can effectively suppress the noise propagation caused by the low precision angular velocity components in coordinate system transformation.Conclusions: The results show that the satellite attitude angular velocity calculated by the combination of multiple astrological instruments can be significantly improved in the whole power spectral density, the power spectral density of gravity gradient trace values calculated by the combined method of multiple astrologers is also significantly improved compared with the single astrologer method. [ABSTRACT FROM AUTHOR]

Objectives: The Badong-Zigui Basin is located in the west of the Three Gorges area, and it is surrounded by four different tectonic units: With the Xuefengshan thick-soil tectonic belt on the south, the Qinling orogenic belt on the north, the Huangling anticline on the east, and the eastern extension of the Sichuan Basin in the west. The Badong-Zigui basin is a north-south syncline structure, the sediments in the basin are dominated by Late Triassic-Late Turassic argillaceous rocks, and the special tectonic setting causes strong tectonic activities in the basin. Methods: Using a three-dimensional gravity inversion algorithm based on Lagrangian multiplier constraints, the local Bouguer gravity anomaly in Badong-Zigui area is inverted, and the underground three-dimensional density structure of Badong-Zigui and adjacent areas is obtained. Results: The inversion results show that the Zigui Basin is a low-density area compared with the surrounding area. The sedimentation thickness in the east is deeper than that in the west, and the sediment density is lower than that in the west. The small and medium earthquakes in the area are basically 4-12 km underground. Conclusions: The north-south and north-east ancient water flows in the northern edge of the Zigui Basin successively provide sources for the sedimentation and filling of the basin, forming a structure with lower material density and deeper deposits in the eastern part of the basin; low-density materials in the east are transported and accumulated to the west in the basin. At the same time, it is squeezed by the eastward extension of the Sichuan Basin, and it is speculated that there is a tendency of east-west movement and compression in the basin. [ABSTRACT FROM AUTHOR]

Objectives: The accuracy of the traditional gravity-geologic method (GGM) for inversion of seafloor topography should be improved. Methods: This paper proposes an improved GGM (iGGM) considering the nonlinear term. The 1 arc minute seafloor topography of the South China Sea is inverted by iGGM, and its accuracy is evaluated through check points to verify the effectiveness. Results: The results show that neglecting nonlinear term of seafloor topography results in a deviation of approximately 50 mGal in mountainous areas with undulation of approximately 2 km. The nonlinear term of seafloor topography could be recovered by the iGGM from short-wavelength gravity anomaly. Conclusions: Compared with the traditional GGM, ETPO1 and SIO V23.1, iGGM has the best accuracy. The root mean square of deviations between iGGM and check points is 130.4 m. Compared with traditional GGM, the improvement of iGGM is 10.8 m near the Huangyan seamount chain, and it is 4.7 m near the Zhongsha Islands. [ABSTRACT FROM AUTHOR]

In the past two decades, satellite gravimetry has been widely developed to map the mass distribution on the Earth system. It helps human beings to have a deeper understanding of the dynamic processes that occur on the Earth's surface (e.g., atmosphere, hydrosphere, ocean, and polar ice sheets). This paper reviews the development history of challenging minisatellite payload, gravity recovery and climate experiment, gravity field and steady-state ocean circulation explorer, and gravity recovery and climate experiment follow-on. We briefly describe the research progress and problems of these gravity satellite missions. In order to overcome the shortcomings of the gravity satellites mentioned above, international research institutions propose numerous plans and simulation analyses for the next generation gravity mission (NGGM). This paper sorts out the task concepts, expected accuracy, and status for 12 kinds of NGGM proposed by international agencies. In order to introduce NGGM more clearly and grasp its current progress, we divide NGGM into four categories according to constellation configuration and satellite payload technology, including Sharifi-type gravity satellite constellation, Bender-type gravity satellite constellation, Satellitelink gravity satellite constellation, and Cold-atom gravity satellite constellation. This paper aims to sort out and summarize the NGGM to grasp the progress at this stage and presents some future perspectives for NGGM. [ABSTRACT FROM AUTHOR]

Ａｉｍｉｎｇ ａｔ ｔｈｅ ｐｒｏｂｌｅｍ ｏｆ ｓｔｕｃｋ ｉｎ ｔｈｅ ｆｒｏｎｔ ｗｉｎｄｏｗ ｇｌａｓｓ ｏｆ ａ ＳＵＶ , ｔｈｅ ｒｉｇｉｄ￣ｆｌｅｘｉｂｌｅ ｃｏｕｐｌｅｄ ｍｕｌｔｉ￣ｂｏｄｙ ｄｙｎａｍｉｃｓ ｍｏｄｅｌ ｏｆ ｔｈｅ ｓｈｅａｖｅ ｔｙｐｅ ｇｌａｓｓ ｌｉｆｔｅｒ ｗａｓ ｅｓｔａｂｌｉｓｈｅｄ, ｔｈｅ ｐｅｒｆｏｒｍａｎｃｅ ｉｎｄｅｘｅｓ ｓｕｃｈ ａｓ ｇｌａｓｓ ｄｅｆｌｅｃｔｉｏｎ ｄｉｓｐｌａｃｅｍｅｎｔ ａｎｄ ｗｉｒｅ ｒｏｐｅ ｔｅｎｓｉｏｎ ｗｅｒｅ ｒｅ￣ ｓｅａｒｃｈｅｄ. Ｍｏｄｅｌ ａｃｃｕｒａｃｙ ｗａｓ ｖｅｒｉｆｉｅｄ ｔｈｒｏｕｇｈ ｔｈｅ ｌｉｆｔ ｔｅｓｔ ｂｅｎｃｈ, ｔｈｅ ｐａｒａｍｅｔｅｒｓ ｓｕｃｈ ａｓ ｒａｉｌ ｐｏｓｉｔｉｏｎ, ｇｕｉｄｅ ｓｅａｌ ｆｒｉｃｔｉｏｎ ｆｏｒｃｅ ａｎｄ ｓｌｏｔ ｓｅａｌ ｆｒｉｃｔｉｏｎ ｆｏｒｃｅ ｗｅｒｅ ｐａｒａｍｅｔｅｒｉｚｅｄ, ｃｏｍｂｉｎｅｄ ｗｉｔｈ ｔｈｅ Ｌａｔｉｎ ｈｙｐｅｒｃｕｂｅ ｄｅｓｉｇｎ ｍｅｔｈｏｄ ｏｆ Ｉｓｉｇｈｔ ｆｏｒ ｅｘｐｅｒｉｍｅｎｔａｌ ｄｅｓｉｇｎ, ａ ｓｅｃｏｎｄ￣ｏｒｄｅｒ ｒｅ￣ ｓｐｏｎｓｅ ｓｕｒｆａｃｅ ａｐｐｒｏｘｉｍａｔｉｏｎ ｍｏｄｅｌ ｆｏｒ ｅａｃｈ ｉｎｄｅｘ ｗａｓ ｅｓｔａｂｌｉｓｈｅｄ. Ｂａｓｅｄ ｏｎ ｔｈｅ ｒｅｓｐｏｎｓｅ ｓｕｒｆａｃｅ ｍｏｄｅｌ, ｔｈｅ ｓｅｃｏｎｄ ｇｅｎｅｒａｔｉｏｎ ｎｏｎ￣ｄｏｍｉｎａ￣ ｔｅｄ ｇｅｎｅｔｉｃ ａｌｇｏｒｉｔｈｍ ｗａｓ ｕｓｅｄ ｔｏ ｏｐｔｉｍｉｚｅ ｔｈｅ ｐｅｒｆｏｒｍａｎｃｅ ｏｆ ｔｈｅ ｇｌａｓｓ ｌｉｆｔｅｒ. Ｔｈｅ ｏｐｔｉｍｉｚａｔｉｏｎ ｒｅｓｕｌｔｓ ｉｎｄｉｃａｔｅ ｔｈａｔ ｔｈｅ ｇｌａｓｓ ｓｔｕｃｋ ｐｈｅｎｏｍｅ￣ ｎｏｎ ｄｉｓａｐｐｅａｒｓ, ｔｈｅ ｄｅｆｌｅｃｔｉｏｎ ｄｉｓｐｌａｃｅｍｅｎｔ ｏｆ ｔｈｅ ｍｅａｓｕｒｉｎｇ ｐｏｉｎｔ ｏｎ ｔｈｅ ｇｌａｓｓ, ｔｈｅ ｄｅｆｌｅｃｔｉｏｎ ｄｉｓｐｌａｃｅｍｅｎｔ ｏｆ ｔｈｅ ｌｏｗｅｒ ｍｅａｓｕｒｉｎｇ ｐｏｉｎｔ, ａｎｄ ｔｈｅ ｐｕｌｌｉｎｇ ｆｏｒｃｅ ｏｆ ｔｈｅ ｓｔｅｅｌ ｗｉｒｅ ｒｏｐｅ ａｒｅ ｒｅｄｕｃｅｄ ｂｙ ４７. ６％, ３３. ３％, ９. ６％, ｕｎｄｅｒ ｔｈｅ ｃｏｎｄｉｔｉｏｎ ｏｆ ｓａｔｉｓｆｙｉｎｇ ｔｈｅ ｇｌａｓｓ ｒｉｓｅ ｔｉｍｅ, ｔｈｅ ｇｌａｓｓ ｌｉｆｔｉｎｇ ｐｅｒｆｏｒｍａｎｃｅ ｉｓ ｓｉｇｎｉｆｉｃａｎｔｌｙ ｉｍｐｒｏｖｅｄ. [ABSTRACT FROM AUTHOR]

Satellite gravimetry is an efficient technical means to detect the global consistent, high-precision and high-resolution Earth’s gravity field, mainly including high-low satellite-to-satellite tracking (SST-hl), low-low satellite-to-satellite tracking (SST-ll) and satellite gravity gradiometry (SGG). We summarize the main methods to recover the Earth’s gravity field from satellite gravimetry technologies (including SST-hl, SST-ll, SGG and multi-mode combination), and review the latest progress in constructing the static and time-variable gravity field models using challenging mini-satellite payload(CHAMP),gravity recovery and climate experiment(GRACE)/GRACE follow-on(GRACE-FO) and gravity field and steady-state ocean circulation explorer(GOCE) satellite gravity measurements. And the accuracies of the current representative static and time-variable gravity field models are analyzed and evaluated. It is expected to provide reference for the study of the Earth’s gravity field and its geoscience application in the future. [ABSTRACT FROM AUTHOR]

Based on the flexural isostasy model of the lithosphere, a 1°×1° model of lithospheric effective elastic thickness over the global seafloor was calculated by the Moving Window Admittance Technique (MWAT) method, using bathymetry and gravity anomalies derived from altimetry data. The results show that the lithospheric effective elastic thickness over the seafloor is generally small. About 70% of the seafloor has an effective elastic thickness of lower than 10 km, and 85.4% are lower than 15 km. The mean and standard deviation of effective elastic thickness is about 10 km and 6.7 km, respectively. The lithosphere with an effective elastic thickness larger than 20 km is mainly located in out rise of the trenches. The lithosphere over the mid-ocean ridge usually has effective elastic thickness of lower than 5km. The strength of lithosphere over the passive continental margin, such as the southern margin of the Australian continent, is also weak. The effective elastic thickness of lithosphere over the seamount area of the Pacific is about 10 to 20 km. [ABSTRACT FROM AUTHOR]

In this paper, a 1'X1' bathymetry model over China Sea and its adjacent areas was formed combining ship soundings, gravity anomalies and vertical gravity gradient anomalies. The ship soundings were used for constraining bathymetry at wavelengths longer than 200 km. The vertical gravity gradient anomalies were used for predicting bathymetry at 100 ~ 200 km wavelength. The gravity anomalies were used for predicting bathymetry at wavelength shorter than 100 km. Compared to ship soundings, the accuracy of the predicted model for the South China Sea and Philippine Sea was evaluated. The results show that the accuracy of the model is better than the ETOPO1, GEBCO and DTU10. In South China Sea, the accuracy of predicted model is consistent with the latest V15. 1 model from SIO. In Philippine Sea, as compared to V15. 1, the accuracy of the model increased by about 8.2%. [ABSTRACT FROM AUTHOR]