A flight test of airborne gravimetry was conducted in Antarctic based on a strapdown inertial airborne gravimeter called SGA02 during the 36th Chinese National Antarctic Research Expedition. This test was aimed at evaluating accuracy of the system, collecting gravity data, and measuring the system’s practicability. Airborne gravimetry is one of the most significant methods in gathering gravity data with mGal-level precision over several kilometers of spatial resolution, which is a kind of strategic resource in the field of geophysics and many other important areas. A lack of southern hemisphere research and geophysical data exists due to the difficult accessibility of the Antarctic region. Since geophysical data of this region can hardly be acquired, the test performed in Antarctic can, in some degree, make up the gap between the gravity data and other geographic features. SGA02 is independently developed by NUDT (National University of Defense Technology), based on integrated SINS/DGPS system (strapdown inertial navigation system and differential global positioning system). In the flight test of the airborne gravimetry in the Antarctic region, SGA02 performed with 1.5 mGal precision (160s of filtering). The constitution of the whole system is introduced and the theory of the strapdown inertial airborne gravimeter is briefly discussed. The data gained from this test is displayed and analyzed, followed by the discussion and evaluation of the results.
Aiming at the problem that the single-axis rotation modulation technology is currently used in gravity measurement, only considering the inertial device's zero bias will restrict gravity measurement accuracy, a single-axis rotation modulation strapdown gravity vector measurement method considering the scale factor error is proposed. This method analyzes the one-way continuous rotation scheme and finds that the up-direction scale factor error stimulates additional attitude errors. To suppress the error and improve the measurement accuracy of the strapdown gravity vector, a dual-position forward and reverse turn-and-stop scheme is adopted, which designs a reasonable rotation path, stop position, and time. The simulation results show that the dual-position forward and reverse turn-and-stop scheme, considering the scale factor, can effectively improve the accuracy of gravity measurement compared with the one-way continuous rotation scheme. This study has great technical reference significance and engineering practice significance and can meet the needs of high-precision airborne and marine gravity measurement.
Gravity field modelling is an important research content in the field of geophysics, as well as a basic digital resource in natural resource exploration. It plays an important role in navigation, airborne geophysical exploration, and geodesic research. In this paper, based on the algorithms of least squares-collocation (LSC) method and inverse distance weighted (IDW) method, considering the limitations of single IDW modelling method in local gravity field modelling, a method of local gravity field modelling combining LSC and IDW is proposed named IDW-LSC. A group of estimated gravity anomaly data can be calculated by conducting the IDW, then the error sequence can be computed from the estimated data and the original data. Fitting the error sequence by using LSC algorithm, an error model of the survey region can be established, which can be used to optimize the gravity anomaly data estimated by IDW interpolation method, a new and optimized gravity model can be computed. In this study, a dataset of gravity anomaly from a test of airborne gravimetry over an area of China is used to verify this new method. The result shows the new method is more reliable than single method and promising to promote the precision of the gravity model.
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