## 3 Results
### General Characteristics and Energy Flux
#### 3.1.1 Surface Displacement Due to Internal Tides
The red lines represent the locations of the profiles shown in Figure 4 along the internal tides’ propagation direction. occurs. Note that the east-west internal tides are suppressed as our analysis was based on filtered satellite along-track data [24], considering that the tracks are generally along the south-north direction. In the Red Sea, we identified three main sources of internal tides as indicated by the blue rectangles in Figure 3: the northern Red Sea, southern Red Sea, and Strait of Bab-el-Mandeb (BAM); these locations are in agreement with those identified in previous studies [39; 40; 41]. A series of hourly snapshots reveals more details about the generation sites and propagation directions (not shown). Specifically, in the northern Red Sea, internal tides propagate into the Gulf of Suez and the Gulf of Aqaba. In the southern Red Sea, they are generated at Dahlak Island and propagate toward the northeast until they reach the coastline. In BAM, internal tides are generated when barotropic tides pass through the strait; the generated internal tides have an amplitude about five-times that of the tides in the southern Red Sea. Although internal tides in the southern Red Sea are weaker in terms of the amplitude, they can propagate over more than 300 km, which is a much wider range than those of the internal tides generated in the northern Red Sea and BAM. In the Arabian (or Persian) Gulf, we identified two sources of internal tides near the Strait of Hormuz and northern Qatar (as indicated by the two orange boxes in Figure 3). However, because of the shallow water depth and complex coastline, internal tides derived from satellite data may be contaminated by large uncertainties in the case of this basin. After providing a general description of the internal tides in the study domain, we focus now on studying the propagation of the internal tides in specific directions. Figure 4a-f depicts the amplitudes and phases of the internal tides with the bottom topography along the two red Lines A and B highlighted in Figure 3. Instead of a superposition of the first three waves, we considered only the maximum wave because the superposition of phases is insignificant, and the maximum wave describes the major features of the internal tides. The phase distribution along Line A is shown in Figure 4a. Here, two black arrows indicate the northward direction of propagation, in which case, the phase gradually increases from 0\({}^{\circ}\) to 360\({}^{\circ}\) and then sharply drops to 0. However, not all the phase falls rapidly. Although only the maximum wave was considered, the waves along Line A may have originated from different sources. Figure 4b,c shows the amplitude and bathymetry along the same transect. Note that the gray shading represents the area with significant internal tides, located between 11\({}^{\circ}\)N and 15\({}^{\circ}\)N and peaking around 13\({}^{\circ}\)N. Similarly, Figure 4d-f illustrates the same properties along the red Line B. The amplitude along this line reaches 0.77 cm at 17\({}^{\circ}\)N, and the consistency between the steepness of the topography and the amplitude suggests that the internal tides are generated from the area with steep topography. Figure 4: Changes of mode-1 \(M_{2}\) internal tides along the red Lines A and B in Figure 3. (**a**,**d**) Internal tides’ phase versus latitude. The propagation direction could be identified from the distribution of the phase, as indicated by the arrow. (**b**,**e**) Internal tides’ amplitude versus latitude. Amplitude here is the displacement in sea surface caused by internal tides. (**c**,**f**) Water depth versus latitude. The gray shading area outlines the area with strong internal tides.