## 3 Results
### Sensitivity Model Experiments  
To further analyze the characteristics of the tidal currents, we conducted a set of sensitivity experiments to assess the effects of dynamical factors, such as winds, tides, and river discharges. Figure 10 shows the monthly averaged flow fields for the sensitivity experiments. In the control experiment (CTR), there was a strong alongshore current flowing southwestward, driven by all forcings: river discharges, northeast winds, and tides. Apparently, the northeast wind was the dominant forcing, pushing the currents toward the coast. In the no_wind case, the river runoff was dominant, turning to the west of the PRE and forming a plume flow pattern. Compared to the CTR, the alongshore current in the no_wind case was further offshore. In the no_tide case, the flow pattern was very similar to the CTR experiment, because the tide effect was mostly filtered out by monthly averaging. In the no_river case, the wind effect also dominated, except that the river runoff disappeared within the PRE (Figure 10h). To identify the effects of winds, tides, and river discharges, the differences between the CTR and the three sensitivity experiments are shown in the right panel of Figure 8. Obviously, the wind effect was dominant. It produced northwestward currents in the offshore region, an alongshore current in the nearshore region, and an inflow within the PRE, inhibiting river runoff (Figure 10c). As expected, the tide had an insignificant effect on the monthly mean flow. The river discharge showed an outflow from the PRE, turning toward the west shore. It can be noted that both no_wind and no_river cases indicated the effects of river discharge, but their patterns were indeed different. Figure 10b,i present the flow pattern without and with the nonlinear interactions between the winds and river plume, respectively.  
The standard deviations are calculated for each sensitivity experiment and the difference between the control and sensitivity experiments are presented in Figure 11. In the control experiment, the standard deviation is high within the PRE related to the strong tidal flow reversal. To the left-hand side of the PRE mouth, the coastal jet also shows a relatively high standard deviation compared to the shelf. Over the shelf, the standard deviation caused by tides and winds becomes weak and uniform, with an amplitude of about 0.3 cm/s. The differences between the control and sensitivity experiments demonstrate the effect of the corresponding factors. We see that the effect of tides is mainly within the PRE and coastal zones, while the river can affect the PRE and the coastal jet. In contrast, the wind effect is dominated on the continental shelf.  
Figure 9: Comparison between model and radar radial components of the tidal ellipse at (**a**) Shangchuan and (**b**) Wanshan stations. Points in area A, red circles; points in area B, blue circles; points in area C, green circles.  
Figure 10: The averaged flow in the control experiments (the left column; (**a**,**d**,**g**)), sensitivity experiments (the middle column; (**b**,**e**,**h**), including tests without wind, tide, or river discharge), and the difference between control and sensitivity experiments (the right column; (**c**,**f**,**i**)).