Dosso Stan E, Heard Garry J, Vinnins Michael
School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W 3P6, Canada.
J Acoust Soc Am. 2002 Dec;112(6):2721-34. doi: 10.1121/1.1516758.
This paper investigates the use of geophones mounted on the surface of Arctic sea ice for estimating the bearing to acoustic sources in the water column. The approach is based on measuring ice seismic waves for which the direction of particle motion is oriented radially outward from the source. However, the analysis is complicated by the fact that sea ice supports several types of seismic waves, producing complex particle motion that includes significant nonradial components. To suppress seismic waves with transverse particle motion, seismic polarization filters are applied in conjunction with a straightforward rotational analysis (computation of particle-motion power as a function of angle). The polarization filters require three-dimensional (3D) measurements of particle motion, and apply theoretical phase relationships between vertical and horizontal components for the various waves types. In addition, the 180 degrees ambiguity inherent in the rotational analysis can be resolved with 3D measurements by considering particle motion in the vertical-radial plane. Arctic field trials were carried out involving two components. First, a hammer source was used to selectively excite the various ice seismic waves to investigate their propagation properties and relative importance in bearing estimation. Second, impulsive acoustic sources were deployed in the water column at a variety of bearings and ranges from 200-1000 m. For frequencies up to 250 Hz, source bearings are typically estimated to within an average absolute error of approximately 100.
本文研究了安装在北极海冰表面的地震检波器用于估计水柱中声源方位的情况。该方法基于测量冰面地震波，其质点运动方向从震源沿径向向外。然而，由于海冰支持多种类型的地震波，产生包括显著非径向分量的复杂质点运动，使得分析变得复杂。为了抑制具有横向质点运动的地震波，将地震极化滤波器与一种简单的旋转分析（计算质点运动功率作为角度的函数）结合使用。极化滤波器需要对质点运动进行三维（3D）测量，并应用各种波型的垂直和水平分量之间的理论相位关系。此外，通过考虑垂直-径向平面内的质点运动，利用3D测量可以解决旋转分析中固有的180度模糊性问题。进行了涉及两个部分的北极现场试验。首先，使用锤击震源有选择地激发各种冰面地震波，以研究它们的传播特性以及在方位估计中的相对重要性。其次，在水柱中以各种方位和200 - 1000米的距离部署脉冲声源。对于高达250赫兹的频率，声源方位通常估计的平均绝对误差约为100以内。
