Research of Interannual Variability of M₂ Internal Tide in Luzon Strait by Multi-Satellite Altimetry Data

Internal tides are internal waves with ocean tidal frequency, which play an important role in marine processes such as seawater vertical nutrient transport and seawater mixing. Understanding the spatial and temporal variations of internal tides is essential for studying internal tides. The Luzon Strait is one of the most frequently occurring areas in the global ocean. This study utilizes seven satellite altimeter data from 2017 to 2021 to investigate the annual variability of the M₂ internal tides in the Luzon Strait. The plane wave fitting method was used to extract M₂ internal tide models in different years, and analyze the interannual variation characteristics of the M₂ internal tide in the Luzon Strait and the influence of the Kuroshio current on the interannual variation of the M₂ internal tide. The results indicate significant annual variability in the M₂ internal tide in the Luzon Strait, with multi-wave interference enhancing this variability. The results show that the interannual variability characteristics of the M₂ internal tide amplitude in the east and west sides of the Luzon Strait are opposite, with an increase in the west side leading to a decrease in the east side. The average amplitude of the M₂ internal tide in the west side of the Luzon Strait is generally greater than in the east side, but it is reversed in 2020 due to the abnormal changes of the Kuroshio current in the Luzon Strait.