To recognize the environmental effects on underwater acoustic localization in deep sea and improve the measurement system performance against environmental variations, an simulation method for localization performance evaluation under different oceanographic conditions was presented, in which the sound filed calculation, error propagation and crossing solution were integrated by modelling, and the effects of seasonal environmental variation on localization performance were discussed in the case of Western Pacific. According to simulation results, when the receiving depth was near the surface, the sound channel showed different models in summer and winter, such that the accuracy was worse in summer influnced by seasonal thermocline and better in winter influnced by surface duct, the difference of root mean square error (RMSE) beyond 50 m; when the receiving depth was in the upper ocean, the localization performance had an obviously seasonal change caused by the active range of direct wave, and the accuracy was better in winter than that in summer, the difference of RMSE was 15−20 m; when the receiving depth was near the bottom, the better accuracy was obtained using reliable acoustic path, and the localization performance had little change with season. This work indicates that the seasonal environmental variation induces differences in the sound channel as well as the arrival acoustic information, the error propagation and crossing solution for the localization in the half convergence zone area of deep sea, then exert significant effects on localization performance as the receiving depth in the upper ocean.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |