Abstract
The classical harmonic analysis (CHA) method only can be used to obtain the harmonic constants (amplitude and phase) of ocean tide loading displacement (OTLD). In fact, there are significant seasonal variations in the harmonic constants of OTLD. A moving harmonic analysis (MHA) method is proposed, which can effectively capture the seasonal variation of OTLD parameters. Based on 5 years of kinematic coordinate time series in direction U of six Global Positioning System (GPS) stations in Hong Kong, the MHA method is used to explore the seasonal variation of the OTLD parameters of the 6 principal tidal constituents (M2, S2, N2, K1, O1, Q1). The influence of mass loading on the seasonal variation of OTLD parameters is analyzed. The results show that there are obviously seasonal variations in OTLD parameters of the 6 principal tidal constituents in Hong Kong. The OTLD’s amplitude’s changes of the 6 principal tidal constituents are around 4–25.1% and the oscillation ranges of OTLD’s phase parameters vary from 8.8° to 20.4°. Among the seasonal variations of OTLD parameters, the annual signal, the semi-annual signal, and the ter-annual signal are the most significant. By analyzing the influence of atmospheric loading on the seasonal variation of OTLD parameters, it is found that atmospheric loading has certain contribution to the seasonal variation of OTLD parameters. Hydrological loading and non-tidal ocean loading have little influence on the seasonal variation of OTLD parameters.
Highlights
Tidal forces can deform the earth, causing solid earth tide and ocean tide
This paper aims to study the seasonal variation of ocean tide loading displacement (OTLD) parameters using the moving harmonic analysis (MHA) method based on the kinematic coordinate time series of the direction U in Hong Kong, and to analyze the influence and contribution of mass loading to the seasonal changes of OTLD parameters
The MHA method is proposed to study the seasonal variation of OTLD parameters in Hong Kong
Summary
Tidal forces can deform the earth, causing solid earth tide and ocean tide. The periodic redistribution of ocean mass due to ocean tide results in a periodic loading of the solid earth known as ocean tide loading (OTL) [1,2]. Most of the methods to estimate the ocean tide loading displacement (OTLD) are to obtain the harmonic constants (amplitude and phase) of each tide constituent by classical harmonic analysis (CHA) [3,4,5,6]. Many studies have found that the harmonic constants of each tide constituent have significant seasonal variation rather than a constant value [7,8,9,10], which will indirectly lead to the seasonal variation of OTLD parameters. When performing precise data processing, the seasonal variation of OTLD parameters is an important factor to be considered
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