## 3 Results and Discussion
### Comparison Results of TL Calculations
Figure 10: Comparison of the model and actual TL under different SD and frequency on 1 February: (**a**) f = 50 Hz, SD = 100 m; (**b**) f = 50 Hz, SD = 300 m; (**c**) f = 50 Hz, SD = 500 m; (**d**) f = 400 Hz, SD = 100 m; (**e**) f = 400 Hz, SD = 300 m; (**f**) f = 400 Hz, SD = 500 m. When the SD was 100 m, the difference between the TL calculated by the model and the TL calculated by the actual ocean front was very small at low and high frequencies. At 300 m, only on February 1 st (Figure 10b,e), the calculation results of low frequency and high frequency showed a small difference after passing the frontal zone. At 500 m, in terms of the overall trend, the results of the model and the actual results also showed many similarities. Figure 11: Comparison of the model and actual TL under different SD and frequency on 1 July: (**a**) f = 50 Hz, SD = 100 m; (**b**) f = 50 Hz, SD = 300 m; (**c**) f = 50 Hz, SD = 500 m; (**d**) f = 400 Hz, SD = 100 m; (**e**) f = 400 Hz, SD = 300 m; (**f**) f = 400 Hz, SD = 500 m. When the SD was 100 m, the difference between the TL calculated by the model and the TL calculated by the actual ocean front was very small at low and high frequencies. At 300 m, in terms of the overall distribution trend, the results of the model were similar to the calculation results under the actual ocean front environment. At 500 m, in terms of the overall trend, the results of the model and the actual results also showed many similarities. In order to quantify the simulation results of the model, we smoothed the above results through the five-point smoothing method and calculated the root means square error (RMSE) and the percentage with the difference exceeding 10 dB compared with the  
Figure 12: Comparison of the model and actual TL under different SD and frequency on 1 August: (**a**) f = 50 Hz, SD = 100 m; (**b**) f = 50 Hz, SD = 300 m; (**c**) f = 50 Hz, SD = 500 m; (**d**) f = 400 Hz, SD = 100 m; (**e**) f = 400 Hz, SD = 300 m; (**f**) f = 400 Hz, SD = 500 m. When the SD was 100 m, the difference between the TL calculated by the model and the TL calculated by the actual ocean front was very small at low and high frequencies. At 300 m, in terms of the overall distribution trend, the results of the model were similar to the calculation results under the actual ocean front environment. At 500 m, in terms of the overall trend, the results of the model and the actual results also showed many similarities. actual TL (Table 2). It was found that before smoothing, the RMSE of the model was mostly controlled below 6 dB compared with the actual results. Compared with that in previous studies, the effect was further improved. Before smoothing, the percentage with the difference exceeding 10 dB was maintained near 10%, which indicated that the results of our model were less fluctuating than the actual results. In terms of RMSE, all smoothed data were reduced to less than 6 dB, and the percentage with the difference exceeding 10 dB was also further reduced. Except for individual data near 10%, most of the data had been reduced to less than 8%, which verified the effectiveness of the model. As to TL, the calculation results of the model were in good agreement with the actual situation. We calculated the RMSE under different sound source frequencies (Table 3) and different sound source depths (Table 4) to compare the differences between winter (the dates were 0101 and 0201) and summer (the dates were 0701 and 0801). We found that when frequencies were different, the RMSE of TL was close to the same in different seasons, and the seasonal difference of the RMSE caused by the change of frequency was not obvious. When sound source depths were different, the RMSE of TL was different between winter and summer.