海上降雨的水下噪声功率谱特征分析  

Analysis on the underwater noise power spectrum characteristics of rainfall at sea

作　　者：刘贞文[1,2] 文洪涛[1] 牛富强[1] 杨燕明[1] 郑凌虹[1] 

机构地区：[1]国家海洋局第三海洋研究所,福建厦门361005 [2]国家海洋局海岛研究中心,福建平潭350400

出　　处：《应用海洋学学报》2013年第4期509-516,共8页Journal of Applied Oceanography

基　　金：国家海洋局青年基金资助项目(2012444);福建省自然科学基金资助项目(2011J01272)

摘　　要：海上降雨噪声是海洋环境噪声背景的重要间歇性噪声源.它的存在会严重降低许多水声设备的检测效能.国内外对降雨噪声的产生机制及对降雨噪声与降雨类型的量化规律研究仍十分有限.为充分掌握降雨噪声的特性,首先从微观上综合分析了单个水滴落至水面在水中辐射声音的机理,总结了影响声音辐射的3个主要因素：水滴的粒径分布、水滴的终端速度和水滴的入射角度,阐述了室内水滴实验与自然界实际降雨过程中辐射噪声信号的差异,指出了自然界降雨噪声的复杂性.其次从宏观角度建立了降雨强度与噪声功率谱的联系,介绍了降雨强度与噪声功率谱的同步关联方法;统计并提取不同降雨强度下的噪声功率谱类型,并依据谱分布初步分为3大类型,一是降雨强度为0.1～4.0mm/h的噪声功率谱,其特点是在频段13～25 kHz之间存在较高幅度的谱峰;二是降雨强度在4.0～ 18.0 mm/h的噪声功率谱,其特点是除继续存在13 ～25 kHz的谱峰外,频段2～ 10 kHz的功率谱级也迅速增加;三是降雨强度大于18.0 mm/h的噪声功率谱,其特点是在整个频带上谱级都较高,比无雨时的背景噪声功率谱级增加了20 ～ 30 dB.When precipitation falls on the water surface at sea,an acoustic signal with broadband frequency and strong intensity will be radiated in oscillogram pattern.It is now known as rainfall noise.As one of loudest sources,the intermittent rainfall noise can decrease the detection ability of sonar,affect the application frequency bands of underwater acoustic communication and reduce using performance of part of underwater sound equipment.In this paper,the underwater sound radiation mechanism of water drops impacting on the water surface is analyzed firstly.Then,the major difference of sound features between artificial water-drop experiments and outdoor actual rainfall is inducted and the three main impact factors for rainfall noise such as raindrop size distribution,terminal velocity and incidence angle are introduced.Further,a matching method between power spectrum of rainfall noise and the synchronous rainfall intensities is studied and their relationship is established.According to the shape of spectral curve,the sound spectrum can be divided into 3 groups：（1） a higher-level spectral peak in the frequency band of 13 ～ 25kHz,which generally occurs during the period of drizzle that rainfall rates are 0.1 ～ 4.0 mm/h,（2） the sound spectral level increases quickly in frequency band of 2 ～ 10 kHz as well as the spectral peak in frequency band of 13 ～ 25 kHz,which generally occurs during the period of rainfall rates at 4.0 ～ 18.0 mm/h,（3） the sound spectrum curve is seen as negative trend on the slope in the frequency band of 1 ～ 30 kHz during the period of rainfall rates beyond 18 mm/h.It is worth noting that the value increases at least 20 ～ 30 dB than the background noise in the period of rainlessness.

关 键 词：海洋声学 降雨 噪声 强度 功率谱 

分 类 号：P733.2[天文地球—物理海洋学]