In this study, we compare six commonly used methods for the downward continuation of airborne gravity data. We consider exact and noisy simulated data on grids and along flight trajectories and real data from the GRAV-D airborne campaign. We use simulated and real surface gravity data for validation. The methods comprise spherical harmonic analysis, least-squares collocation, residual least-squares collocation, least-squares radial basis functions, the inverse Poisson method and Moritz’s analytical downward continuation method. We show that all the methods perform similar in terms of surface gravity values. For real data, the downward continued airborne gravity values are used to compute a geoid model using a Stokes-integral-based approach. The quality of the computed geoid model is validated using high-quality GSVS17 GPS-levelling data. We show that the geoid model quality is similar for all the methods. However, the least-squares collocation approach appears to be more flexible and easier to use than the other methods provided that the optimal covariance function is found. We recommend it for the downward continuation of GRAV-D data, and other methods for second check.

在这项研究中，我们比较了六种常用的机载重力数据向下延续方法。我们考虑网格和飞行轨迹上的精确和嘈杂的模拟数据以及来自 GRAV-D 空降战役的真实数据。我们使用模拟和真实的表面重力数据进行验证。方法包括球谐分析、最小二乘搭配、剩余最小二乘搭配、最小二乘径向基函数、逆泊松法和莫里茨解析向下延拓法。我们展示了所有方法在表面重力值方面的表现相似。对于真实数据，使用基于斯托克斯积分的方法，使用向下持续的空中重力值来计算大地水准面模型。使用高质量的 GSVS17 GPS 水准测量数据验证了计算的大地水准面模型的质量。我们表明，所有方法的大地水准面模型质量都是相似的。但是，只要找到最优协方差函数，最小二乘搭配方法似乎比其他方法更灵活、更易于使用。我们推荐它用于 GRAV-D 数据的向下延续，以及其他方法进行二次检查。