## 1 _Introduction_  
The generation, propagation, and dissipation of internal waves have been extensively studied and remain a major topic of research [1, 2]--especially internal tides, which are internal waves with tidal frequencies and play a crucial role in a variety of processes, including the transport of heat, freshwater, nutrients, pollutants, and dissolved gases through diapycnal mixing [3]. Further, low-mode internal tides can travel long distances of approximately 1000 km from their generation sites [4, 5]. Thus, understanding the cascading processes of internal tides is important for improving our understanding of oceanic processes and for predicting the effects of climate change on the ocean [6]. According to numerical simulations and observational studies on the cascading of low-mode internal tides [7, 8, 9, 10], there are major contributors, such as mesoscale currents and eddies, which are prevalent in oceans. These mesoscale fields interact with internal tides during propagation, breaking down the low-mode internal tides into higher modes and/or harmonics via nonlinear interactions, including triad resonance [11, 12, 13]. Interactions with mesoscale eddies are particularly critical for internal waves, as they can cause deformation and eventual breaking [14], increase the internal wave energy at the surface, decrease the vertical wavelength of internal waves [15], influence the propagation of internal tides near generation sites like the Luzon Strait [16, 17], and intensify diapycnal mixings [18]. The modulations of internal waves or internal tides via various interactions with current fields and mesoscale eddies include variations in the amplitude, phase, direction, frequencies, and energy dissipation [19; 20; 21]. These time-varying external conditions induce the modulations of internal tides with spatiotemporal characteristics [17; 21]. According to moored current observations [21], the interference of internal tides causes different effects on the coherent motions of semidiurnal and diurnal tides; semidiurnal tides are clearly amplified, while diurnal tides are rather weakened. On the incoherence of internal tides, a major factor was observed to be the influence of mesoscale eddies [21], to which semidiurnal internal tides were more sensitive. Mesoscale eddies modulate currents and stratification, and current-related mesoscale eddies more greatly affect the refraction of internal tides [17] by changing their phase speeds. Since mesoscale eddies induce anomalies in temperature, salinity, and velocities [22], the level of modulation of internal tides could be variable in the interior of eddies. Thus, examining the modulation of internal tides inside a mesoscale eddy could enhance the understanding of spatiotemporal characteristics of interactions between internal tides and mesoscale eddies. To this end, we use the underwater glider measurements within a targeted mesoscale anticyclonic eddy (Figure 1), obtained during only 11 days from 8 September to 19 September 2018 (Figure 2). Since our dataset is spatiotemporally restricted for conventional dynamic mode decompositions, we present a new methodology combining wavelet and complex network approaches. Wavelet analysis is a powerful technique for analyzing non-stationary signals or time series data with time-varying frequency content. There are several advantages over traditional power spectral analysis methods, such as the Fourier transform or periodogram. Firstly, it provides both time and frequency information [23], allowing for better localization of transient or non-stationary features in complex signals such as oceanic oscillatory phenomena. Secondly, it can capture features at different scales or resolutions, providing a more comprehensive understanding of the signal's structure [24]. Thirdly, it can efficiently detect and characterize abrupt changes, discontinuities, or singularities in a signal [25].