用定深爆炸声源反演海底声学参数
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摘要
根据2014年在南中国海开展声学试验的定深爆炸宽带声信号数据进行海底地声参数反演.考虑到不同海底声参数对不同声场物理参数的敏感程度不同以及不同海底声参数对不同反演方法的敏感程度亦不同,综合应用2种反演方法得到不同底质声参数:(1)根据接收的直达波和海底反射波计算得到关注海域的海底反射系数进而反演得到海底声阻抗;(2)实验海区的海底地形为大陆坡,选取Hamilton总结的关于沉积物声速与沉积物密度关系的经验公式,结合沉积物声阻抗与沉积物声速、沉积物密度的关系,进而反演得到沉积物声速和沉积物密度.沉积物声学参数的取样测量是在实验室条件下进行的,温度为23℃,大气压1×105Pa,由于沉积物孔隙海水是决定沉积物声速的关键且受温度压强变化的影响显著,本研究利用沉积物声速与孔隙海水声速的比值即使在温度压强变化的情况下较稳定的特点,可对沉积物声速在实验室条件和海底原位条件进行校正.校正到海底温度和压强后,反演结果与沉积物取样的实测结果和Hamilton总结的结果吻合得相当好:(1)声阻抗的反演结果为2.065 6×10~5g/(cm2·s),修正后的沉积物取样结果则为2.046 0×10~5g/(cm~2·s),Hamilton总结的结果为2.238 0×10~5g/(cm~2·s);(2)声速的反演结果为1 482.6m/s,修正后的沉积物取样结果为1 467.5 m/s,Hamilton总结的结果为1 502.8 m/s;(3)密度的反演结果为1.393 2 g/cm3,沉积物取样结果为1.400 0 g/cm~3,Hamilton总结的结果为1.489 0 g/cm3.
This paper provides the geoacoustic inversion results used broadband data from underwater explosion at fixed depth in an Acoustics Experiment in the South China Sea,2014. Considering sensitivity differences of acoustic parameters of sediments to physical parameters of sound field and geoacoustic inversion methods,2 approachesare used respectively for different acoustic parameters of sediments. Firstly,acoustic impedance can be achieved by vertical bottom reflective coefficients from sound reflected of sea bottom divided by directly arrived sound. Secondly,sound velocity and density can also be achieved by combining Hamilton empirical equation to the relationship between acoustic impedance,sound velocity and density of sediments. The Hamilton empirical equation is about sound velocity and density of sediments and another key is to choose appropriate terrain which is continental terrace in this experiment. On different sea bottom,acoustic parameters of sediment samples are measured in laboratory conditions of temperature 23℃ and standard atmospheric pressure 1-atm. As a result,acoustic parameters especially sound velocity need to be corrected to match different temperatures and pressures. Sound velocity is corrected successfully,in this paper,due to the fact that porewater of sediment critically determines sound velocity and the ratio of the sediment sound velocity to the porewater sound velocity is relatively stable even in the conditions that the temperature and pressure varies greatly. Inversion results appear to be well consistent when compared with in situ gravity core measurements and with data from Hamilton. In detail,in terms of acoustic impedance,the gravity core result after correction and the Hamilton conclusion are 2. 065 6 × 10~5,2. 046 0 ×10~5and 2. 238 0 × 105 g /( cm~2·s),respectively. In terms of sound velocity,the gravity core result after correction and the Hamilton conclusion are1 482. 6,1 467. 5 and 1 502. 8m / s,respectively. In terms of sediment density,the gravity core result after correction and the Hamilton conclusion are 1. 393 2,1. 400 0 and 1. 489 0 g / cm3,respectively.
This paper provides the geoacoustic inversion results used broadband data from underwater explosion at fixed depth in an Acoustics Experiment in the South China Sea,2014. Considering sensitivity differences of acoustic parameters of sediments to physical parameters of sound field and geoacoustic inversion methods,2 approachesare used respectively for different acoustic parameters of sediments. Firstly,acoustic impedance can be achieved by vertical bottom reflective coefficients from sound reflected of sea bottom divided by directly arrived sound. Secondly,sound velocity and density can also be achieved by combining Hamilton empirical equation to the relationship between acoustic impedance,sound velocity and density of sediments. The Hamilton empirical equation is about sound velocity and density of sediments and another key is to choose appropriate terrain which is continental terrace in this experiment. On different sea bottom,acoustic parameters of sediment samples are measured in laboratory conditions of temperature 23℃ and standard atmospheric pressure 1-atm. As a result,acoustic parameters especially sound velocity need to be corrected to match different temperatures and pressures. Sound velocity is corrected successfully,in this paper,due to the fact that porewater of sediment critically determines sound velocity and the ratio of the sediment sound velocity to the porewater sound velocity is relatively stable even in the conditions that the temperature and pressure varies greatly. Inversion results appear to be well consistent when compared with in situ gravity core measurements and with data from Hamilton. In detail,in terms of acoustic impedance,the gravity core result after correction and the Hamilton conclusion are 2. 065 6 × 10~5,2. 046 0 ×10~5and 2. 238 0 × 105 g /( cm~2·s),respectively. In terms of sound velocity,the gravity core result after correction and the Hamilton conclusion are1 482. 6,1 467. 5 and 1 502. 8m / s,respectively. In terms of sediment density,the gravity core result after correction and the Hamilton conclusion are 1. 393 2,1. 400 0 and 1. 489 0 g / cm3,respectively.
引文
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[7]Dosso S E.Quantifying uncertainty in geoacoustic inversion I.A fast Gibbs sampler approach[J].J Acoust Soc Am,2002,111(1):129-142.
[8]Li Z L,Zhang R H.A broadband geoacoustic inversion scheme[J].Chin Phys Lett,2004,21(6):1 100-1 103.
[9]Potty G R,Miller J H,Dahl P H,et al.Geoacoustic inversion results from the ASIAEX East China Sea experiment[J].IEEE J Ocean Eng,2004,29(4):1 000-1 010.
[10]赵梅,胡长青.由爆炸声源及传播损失反演海底声学参数[J].声学技术,2009,28(2):104-108.
[11]林建恒,殷宝友,衣雪.海洋环境噪声快速获取海底表层声速[J].声学技术,2010,29(6):80-81.
[12]Jorge E Q,Stan E D,Jan D,et al.Bayesian geoacoustic inversion using wind-driven ambient noise.[J].Acoust Soc Am,2012,131(4):2 658-2 667.
[13]高伟,王宁,王好忠.2005黄海实验混响垂直相关统计反演海底参数[J].声学学报,2008,33(2):109-115.
[14]Fallat M R,Nielson P L.Hybrid geoacoustic inversion of broadband Mediterranean Sea data[J].J Acoust Soc Am,2000,107(4):1 967-1 977.
[15]Li Z L,Yan J,Li F H,et al.Inversion for the sea bottom acoustic parameters by using the group time delays and amplitude of normal mode[J].Chin J Acoust,2003,22(2):176-183.
[16]Liu J J,Li F H,Peng Z H.Stochastic inversion of seabottom scattering coefficients from shallow-water reverberation[J].Chin Phys Lett,2003,20(12):2 188-2 191.
[17]Parra P C,Guerra R C.Impedance profile and overall attenuation estimation of layered sea bottoms from their normal incidence acoustic reflection response[J].J Acoust Soc Am,1989,85(6):2 388-2 393.
[18]Shaw P R,Orcutt J A.Waveform inversion of seismic refraction data and application to young pacific crust[J].Geophys J R Astron Soc,1985,82:375-414.
[19]Carbone N M,Deane G B,Buckingham M J.Estimating the compressional and shear wave speeds of a shallow water seabed from the vertical coherence of ambient noise in the water column[J].J Acoust Soc Am,1998,103(2):801-813.
[20]Sen M K,Stoffa P L.Nonlinear one-dimensional seismic waveform inversion using simulated annealing[J].Geophysics,1991,56(10):1 624-1 638.
[21]Gingras D F,Gerstoft P.Inversion for geometric and geoacoustic parameters in shallow water:experimental results[J].J Acoust Soc Am,1995,97(6):3 589-3 598.
[22]Potty G R,Miller J H,Lynch J F,et al.Tomographic inversion for sediment parameters in shallow water[J].J Acoust Soc Am,2000,108(3):973-986.
[23]Hamilton E L.Prediction of in-situ acoustic and elastic properties of marine sediments[J].Geophysics,1971,36(2):366-377.
[24]Hamilton E L.Sound velocity and related properties of marine sediments[J].J Acoust Soc Am,1982,72(6):1 891-1 904.
[25]何祚镛,赵玉芳.声学理论基础[M].北京:国防工业出版社,1981:70-72.
[26]布列霍夫斯基.海洋声学[M].山东海洋学院海洋物理系,中国科学院声学研究所水声研究室,译.北京:科学出版社,1983:372-378.
[27]商德江,张仁和.新型宽带爆炸声源及海底参数反演[J].声学技术,2003,22(s2):158-160.
[28]邹大鹏,吴百海,卢博,等.海底沉积物声速实验室测量结果校正研究[J].热带海洋学报,2008,27(1):27-31.
[2]郭永刚,李风华,宫在晓,等.利用近场的船噪声反演海底声参数[J].声学技术,2008,27(5):112-113.
[3]殷宝友,尚尔昌,马力,等.浅海环境噪声垂直相关提取海底反射参数[J].中国科学:物理学力学天文学,2011,41(6):741-748.
[4]李整林,彭朝晖.浅海中海底模型与反演方法的选取[C]//中国声学学会.2003年青年学术会议论文集.北京:中国声学学会,2003:116-118.
[5]Tolstoy A,Chapman N R,Brooke G.Workshop 97 benchmarking for geoacoustic inversion in shallow water[J].J Comp Acoustic,1998,6(1/2):1-28.
[6]Chapman N R,Chin-Bing S,King D,et al.Benchmarking geoacoustic inversion methods for range-dependent waveguides[J].IEEE J Ocean Eng,2003,28(3):320-330.
[7]Dosso S E.Quantifying uncertainty in geoacoustic inversion I.A fast Gibbs sampler approach[J].J Acoust Soc Am,2002,111(1):129-142.
[8]Li Z L,Zhang R H.A broadband geoacoustic inversion scheme[J].Chin Phys Lett,2004,21(6):1 100-1 103.
[9]Potty G R,Miller J H,Dahl P H,et al.Geoacoustic inversion results from the ASIAEX East China Sea experiment[J].IEEE J Ocean Eng,2004,29(4):1 000-1 010.
[10]赵梅,胡长青.由爆炸声源及传播损失反演海底声学参数[J].声学技术,2009,28(2):104-108.
[11]林建恒,殷宝友,衣雪.海洋环境噪声快速获取海底表层声速[J].声学技术,2010,29(6):80-81.
[12]Jorge E Q,Stan E D,Jan D,et al.Bayesian geoacoustic inversion using wind-driven ambient noise.[J].Acoust Soc Am,2012,131(4):2 658-2 667.
[13]高伟,王宁,王好忠.2005黄海实验混响垂直相关统计反演海底参数[J].声学学报,2008,33(2):109-115.
[14]Fallat M R,Nielson P L.Hybrid geoacoustic inversion of broadband Mediterranean Sea data[J].J Acoust Soc Am,2000,107(4):1 967-1 977.
[15]Li Z L,Yan J,Li F H,et al.Inversion for the sea bottom acoustic parameters by using the group time delays and amplitude of normal mode[J].Chin J Acoust,2003,22(2):176-183.
[16]Liu J J,Li F H,Peng Z H.Stochastic inversion of seabottom scattering coefficients from shallow-water reverberation[J].Chin Phys Lett,2003,20(12):2 188-2 191.
[17]Parra P C,Guerra R C.Impedance profile and overall attenuation estimation of layered sea bottoms from their normal incidence acoustic reflection response[J].J Acoust Soc Am,1989,85(6):2 388-2 393.
[18]Shaw P R,Orcutt J A.Waveform inversion of seismic refraction data and application to young pacific crust[J].Geophys J R Astron Soc,1985,82:375-414.
[19]Carbone N M,Deane G B,Buckingham M J.Estimating the compressional and shear wave speeds of a shallow water seabed from the vertical coherence of ambient noise in the water column[J].J Acoust Soc Am,1998,103(2):801-813.
[20]Sen M K,Stoffa P L.Nonlinear one-dimensional seismic waveform inversion using simulated annealing[J].Geophysics,1991,56(10):1 624-1 638.
[21]Gingras D F,Gerstoft P.Inversion for geometric and geoacoustic parameters in shallow water:experimental results[J].J Acoust Soc Am,1995,97(6):3 589-3 598.
[22]Potty G R,Miller J H,Lynch J F,et al.Tomographic inversion for sediment parameters in shallow water[J].J Acoust Soc Am,2000,108(3):973-986.
[23]Hamilton E L.Prediction of in-situ acoustic and elastic properties of marine sediments[J].Geophysics,1971,36(2):366-377.
[24]Hamilton E L.Sound velocity and related properties of marine sediments[J].J Acoust Soc Am,1982,72(6):1 891-1 904.
[25]何祚镛,赵玉芳.声学理论基础[M].北京:国防工业出版社,1981:70-72.
[26]布列霍夫斯基.海洋声学[M].山东海洋学院海洋物理系,中国科学院声学研究所水声研究室,译.北京:科学出版社,1983:372-378.
[27]商德江,张仁和.新型宽带爆炸声源及海底参数反演[J].声学技术,2003,22(s2):158-160.
[28]邹大鹏,吴百海,卢博,等.海底沉积物声速实验室测量结果校正研究[J].热带海洋学报,2008,27(1):27-31.