国际监测系统水听器台站监测能力分析

Analysis of monitoring ability of International Monitoring System hydrophone stations

为有效保障《全面禁止核试验条约》(CTBT)的执行,国际监测系统(IMS)基于大洋海域的水声台站开展水下核爆、邻近海岸的地下核爆和近海面的空中核爆监测。为评估IMS水声台站对核爆和潜艇活动的监测能力,以IMS水听器台站HA11为例,开展IMS水听器台站监测能力研究。依据抛物方程方法进行全球海域传播损失预测,并根据实际历史数据获取的IMS水声台站背景噪声级,以及给定的水下爆炸声源级和10-100Hz潜艇辐射噪声谱级,实现探测水下爆炸声源和潜艇的优质因数估计,从而给出IMS水听器台站对爆炸声源和潜艇活动的监测范围。研究结果表明,对于安静型潜艇,较低的辐射噪声级导致HA11水听器台站监测距离小于1km。对于水下爆炸声源,即便当量仅1kg三硝基甲苯(TNT),监测范围可覆盖北太平洋大部分区域。随着潜艇航速的提高,水声台站探测距离虽有所增加,但仍不足以实现潜艇活动的有效监测。因此,IMS水声台站对正常的潜艇活动探测能力有限,而基于良好的深海声信道和较高的爆炸源级则可实现全球大洋海域和部分近海海域的水下爆炸事件监测。

The International Monitoring System(IMS)is being developed to demonstrate methods to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty(CTBT),using the four technologies specified in the treaty(seismic,hydroacoustic,infrasonic and radionuclide).Hydrophone stations are used to monitor the nuclear explosions underwater,underground near the coast and in the air near the surface of the ocean.To assess hydrophone stations’ability to monitor nuclear explosions and submarines,research based on station HA11 was conducted.Transmission loss of the global ocean was predicted using parabolic method,and the noise level near the IMS hydrophones,the submarine radiation noise source level was investigated in the basis of the historical data.Furthermore,based on the passive sonar equation,the detection range for the submarine and underwater explosion can be calculated from the factor of merit.The results illustrate that,only the quiet submarines less than 1 km distance from HA11 can be detected,whereas the explosions in most area of the North Pacific can be monitored by the station HA11 even though its equivalent weight only 1 kg.When a submarine itself has a higher source level or the source level increases due to the increased speed,it is possible to have a certain detection capability which is still tiny.Therefore,the existing IMS hydrophone stations have limited detection capability for submarines due to the low level of radiated noise of submarines.Since the sound source level of underwater explosions is much higher than that of submarines,most of the explosive signals in global ocean propagate in SOFAR channel and can be monitored by the hydrophone stations.