## 4 Discussion
In addition, the red patch in Box B (Figure 9a) suggests that the energy must have originated from the shelves and subsequently propagated through Box A. Simultaneously, internal tides generated from different source locations meet in Box A, and after interacting, these waves propagate along different directions, moving away from each other. To visualize the interaction process, the changes in waves at an arbitrary point (Point P in Figure 9) are shown in Figure 10a. Waves 1-3 represent the three internal waves traveling in different directions at Point P. The solid lines depict the sum of the three waves. Because of the phase differences, these waves interact with each other, particularly in summer. The sum of the wave height in summer is markedly smaller than the individual heights of any of the three waves. In Figure 10b, Waves 1-3 are almost equal in amplitude, but different in phase, and the height of the winter sum wave is larger than those of Waves 1-3. The propagation and superposition of waves in the whole domain can be observed using more of the consecutive hourly SSH snapshots (not shown here). Moreover, the standard deviations (SDs) of those snapshots are shown in Figure 9e,f, indicating the deviation from the averaged SSH at each point. The SD distribution is similar to that of the surface amplitude of the internal tides in space, and a lower SD may reflect an offsetting of the waves. Figure 10: The 24 h time series of waves at Point P in summer (**a**) and winter (**b**). The dashed lines represent the three waves at Point P. The solid lines are the sum of the three. After passing through Box B along the main axis, the energy flux in summer was lower than that in winter. The reduction in the energy flux in summer is not caused by the superposition of waves, because the internal waves in this region propagate in the same direction and are not likely to offset each other (as indicated by Figure 5b). A plausible reason for this seasonal difference in energy flux is the horizontal variations in stratification in the propagation direction of the internal tides. Several previous studies suggested that variations in stratification may affect the generation of internal tides. [PERSON] [49] investigated the sensitivity of internal tides to changes in stratification through numerical experiments, and [PERSON] and [PERSON] [50] demonstrated that variations in stratification could change the internal tidal field. The white curves shown in Figure 9c,d depict the depth of the maximum \(N^{2}\) in summer and winter, respectively, which varies by 90 m and 30 m within 1000 km, respectively. The pycnocline shows a clear slope in summer, whereas it is flat in winter. When the pycnocline has a slope (in summer), which means the the stratification is not stable in the spatial domain, the low-mode internal tides tend to cascade energy to the higher modes and are more likely to trigger the dissipation of turbulent kinetic energy, which hinders the propagation of internal tides [51]. In contrast, the flat pycnocline in winter provides more stable conditions for the propagation of internal tides over long distances. This inference is applied in Figure 9a-d: along the black line, areas with a low-energy flux correspond to the slopes at the white line. More work is still needed to understand the reasons behind this small energy flux.