用于分析主要分潮振幅和迟角季节变化的“分步式”调和分析方法

近年来，研究表明全球部分海域的主要分潮存在季节变化。然而，由于使用传统调和分析方法时，分潮的选取受时间窗长度影响，因此难以准确分析潮汐的季节变化。本文结合长、短时间窗，提出“分步式”调和分析方法，通过理想实验和验潮站实际数据分析验证了该方法的准确性。将新方法与传统调和分析方法加以对比，发现无论潮汐是否存在季节变化，该方法都能更加准确地计算主要分潮各月的振幅和迟角。新方法不仅可用于分析验潮站水位数据，还可用于内潮平稳性和非平稳性特征的研究。

Two-step harmonic analysis for capturing seasonally-varying amplitudes and phase lags of the predominant tidal constituents

Recent studies have revealed that the predominant tidal constituents have seasonal variations at some locations. However, how to accurately obtain these variations remains a problem for the traditional harmonic analysis (HA) due to the tradeoff between length of time window and resolution of constituents. Therefore, a method named as “two-step HA” is developed in this study, which consists of both long- and short-time-window HA. Through a series of ideal experiments, practical application at two tidal gauges and comparison with the traditional HA, the feasibility and accuracy of the two-step HA are verified: The two-step HA performs better than the traditional HA in estimating monthly amplitudes and phases for the predominant constituents, whether they have seasonal variability or not. In addition to capturing variations of the predominant constituents at tidal gauges, the two-step HA would be useful in investigation of the coherence and incoherence of internal tides.