The “non-harmonicity” problem in residual terrain modelling (RTM) is a challenging issue, causing errors exceeding 200 mGal in the RTM gravity anomaly in rugged areas. Although various methods have been proposed to address this problem, including the condensation method, regularized downward continuation methods with Taylor series expansions (TS) and spherical harmonics (SH), complete harmonic correction (HC) method, closed-form complete HC method, and Kadlec's method, their performances in gravity field determination have not been directly validated. In this study, we reviewed and evaluated these methods, especially for their performance in regional geoid determination. We found that the HC's expression for the closed-form complete method is identical to that under the unlimited Bouguer plate approximation, and Kadlec’s method is equivalent to the condensation method with the same approximation for Bouguer masses. However, the HC associated with the complete HC method shows large differences compared to other methods. This is because the upward and downward continuations in the complete HC method consider an Earth with changing total mass. To address it, we propose a new three-step approach, proved to be equivalent to the HC using the TS method. Then the performance of various HC methods is evaluated in gravity anomaly synthesis and geoid determination over a select region in Colorado, USA. The best result is achieved when using the SH method to compute RTM gravity anomalies, resulting in a geoid accuracy of ~ 1.62 cm. Involving the HC for the height anomaly in the restore procedure slightly improves the accuracy to ~ 1.56 cm.

残余地形建模（RTM）中的“非和谐性”问题是一个具有挑战性的问题，导致崎岖地区的RTM重力异常误差超过200 mGal。尽管已经提出了各种方法来解决这个问题，包括压缩方法、使用泰勒级数展开（TS）和球谐函数（SH）的正则化向下连续方法、完全谐波校正（HC）方法、闭式完全HC方法和Kadlec 的方法，其在重力场测定中的性能尚未得到直接验证。在本研究中，我们回顾和评估了这些方法，特别是它们在区域大地水准面测定中的性能。我们发现，闭式完备法的HC表达式与无限布格板近似下的表达式相同，而Kadlec法与布格质量具有相同近似值的凝聚法等价。然而，与其他方法相比，与完整 HC 方法相关的 HC 显示出很大的差异。这是因为完整 HC 方法中的向上和向下延续考虑了总质量不断变化的地球。为了解决这个问题，我们提出了一种新的三步方法，事实证明与使用 TS 方法的 HC 等效。然后，在美国科罗拉多州选定区域的重力异常合成和大地水准面测定中评估各种 HC 方法的性能。使用 SH 方法计算 RTM 重力异常时可获得最佳结果，大地水准面精度约为 1.62 厘米。在恢复过程中涉及高度异常的 HC 将精度略微提高到约 1.56 厘米。