Strapdown airborne gravimetry (SAG) is one of the most efficient techniques used in geodesy and geophysics for acquiring gravity data on relatively large regions in a faster and cost-effective way or to fill in the gravity data gaps on areas where it is neither practical nor possible to make terrestrial measurements. Recent studies have shown that accuracies of 1 mGal and precision of sub-mGal levels are possible with the strapdown inertial systems modified for gravimetry (e.g., temperature stabilization). Besides the advancements in the instrumentation, data processing and integration algorithms are evolving consistently. This study investigates the contribution of long- and short-wavelength gravity reductions following the remove–restore procedure in the indirect SAG processing, where the gravity disturbance at flight altitude is modeled stochastically as an additional system state in the Kalman filter sense. The proposed method is implemented to the airborne data collected in central Turkey in 2018 with a thermally stabilized strapdown inertial measurement unit of navigation-grade type. The inclusion of the long- and short-wavelength gravity reductions in the SAG processing limits the in-run bias variations of the Z-accelerometer and changes the parameters of the third-order Gauss–Markov gravity state model significantly. Utilization of the reduced gravity disturbance in the processing provides better long-wavelength stability in the solution by reducing the mean bias of about 2.60 to 0.65 mGal between the airborne gravity estimates and a high-resolution global gravity model. Moreover, a remarkable improvement in the internal precision is achieved when the gravity reductions are introduced into the SAG solution. Comparisons at the crossover points demonstrate that the application of gravity reductions yields considerably lower crossover residuals than the standard solution without reductions. The non-adjusted crossover differences of the long- and short-wavelength removed and restored SAG solution result in an RMSE value of 0.79 mGal, that is, 40% better precision than the standard solution.

中文翻译：

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减重在间接捷联航空重力测量处理中的应用

捷联航空重力测量 (SAG) 是大地测量学和地球物理学中最有效的技术之一，用于以更快、更经济的方式获取相对较大区域的重力数据，或者填补既不实用也不实用的区域的重力数据空白。可以进行地面测量。最近的研究表明，1 mGal 的准确度和 sub-mGal 水平的精度可以通过为重力测量（例如，温度稳定）修改的捷联惯性系统实现。除了仪器的进步外，数据处理和集成算法也在不断发展。本研究调查了在间接 SAG 处理中去除 - 恢复程序后长波长和短波长重力减少的贡献，其中飞行高度的重力扰动被随机建模为卡尔曼滤波器意义上的附加系统状态。所提出的方法采用导航级热稳定捷联惯性测量单元，对2018年在土耳其中部采集的机载数据实施。在 SAG 处理中包含长波长和短波长重力减少限制了 Z 加速度计的运行中偏差变化，并显着改变了三阶高斯-马尔可夫重力状态模型的参数。在处理过程中利用减少的重力扰动通过减少空中重力估计和高分辨率全球重力模型之间大约 2.60 至 0.65 mGal 的平均偏差，在解决方案中提供更好的长波长稳定性。而且，将重力降低引入 SAG 解决方案时，内部精度得到了显着提高。交叉点的比较表明，与没有减少的标准解决方案相比，应用重力减少产生的交叉残差要低得多。长波长和短波长去除和恢复的 SAG 溶液的未调整交叉差异导致 RMSE 值为 0.79 mGal，即精度比标准溶液高 40%。