Understanding time-changing tidal characteristics is essential for
numerous practical purposes, such as flood prevention, navigation, and
ocean engineering. Previous studies mainly focus on tidal evolution in
coastal areas while tidal changes in deep water areas receive limited
attention due to the lack of long-term high-frequency sea level records.
In this paper, we extract the inter-annual and decadal tidal variability
in the South China Sea (SCS) from 24 coastal tide gauges and 25-year
satellite altimeter observations using the novel S_TIDE toolbox.
Through numerous sensitivity experiments, it is found that
~17 independent points (IPs) are suitable for extracting
inter-annual and decadal tidal variability in the deep basin of the SCS.
It is also found that tidal variability and sea level variability are
closely correlated in most parts of the SCS. The high correlation
between tidal variability and sea level variability in the central deep
basin of the SCS is associated with the El Niño–Southern
Oscillation(ENSO). The results obtained from satellite data are less
stable and accurate than those obtained from long-term tidal gauge
observations, but the methods described here provide a strong foundation
for future research on time-varying tidal dynamics using the combination
of tide gauges and satellite altimeter data.