BackscatterB [7125]--Offshore Pigeon Point, California

This part of DS 781 presents data for the acoustic-backscatter map of Offshore of Pigeon Point map area, California. Backscatter data are provided as three separate grids depending on mapping system. The raster data files are included in "BackscatterB_7125_OffshorePigeonPoint.zip," which is accessible from http://dx.doi.org/10.5066/F7513W80.
The acoustic-backscatter map of the Offshore of Pigeon Point, California was generated from backscatter data collected by California State University, Monterey Bay (CSUMB), by Fugro Pelagos, and by the U.S. Geological Survey (USGS). Mapping was completed between 2006 and 2009, using a combination of 400-kHz Reson 7125 and 244-kHz Reson 8101 multibeam echosounders, as well as a 234-kHz SWATHplus bathymetric sidescan-sonar system. Within the final imagery, brighter tones indicate higher backscatter intensity, and darker tones indicate lower backscatter intensity. The intensity represents a complex interaction between the acoustic pulse and the seafloor, as well as characteristics within the shallow subsurface, providing a general indication of seafloor texture and composition. Backscatter intensity depends on the acoustic source level; the frequency used to image the seafloor; the grazing angle; the composition and character of the seafloor, including grain size, water content, bulk density, and seafloor roughness; and some biological cover. Harder and rougher bottom types such as rocky outcrops or coarse sediment typically return stronger intensities (high backscatter, lighter tones), whereas softer bottom types such as fine sediment return weaker intensities (low backscatter, darker tones).

本数据集DS 781的此部分提供加利福尼亚州鸽子角近海测绘区域的声散射（acoustic-backscatter）地图数据。依据测绘系统的不同，散射数据分为三个独立网格。栅格数据文件封装于"BackscatterB_7125_OffshorePigeonPoint.zip"中，可通过http://dx.doi.org/10.5066/F7513W80获取。
加利福尼亚州鸽子角近海的声散射地图，由加州州立大学蒙特雷湾分校（California State University, Monterey Bay, CSUMB）、富格罗佩拉戈斯（Fugro Pelagos）以及美国地质调查局（U.S. Geological Survey, USGS）采集的散射数据生成。测绘工作于2006至2009年间完成，采用了400kHz Reson 7125与244kHz Reson 8101多波束测深仪（multibeam echosounders），以及234kHz SWATHplus测深侧扫声呐系统。在最终生成的影像中，色调越亮代表散射强度越高，色调越暗则代表散射强度越低。该强度反映了声波脉冲与海底及浅地表内部特征之间的复杂相互作用，可大致指示海底的质地与组成。散射强度受以下因素影响：声源级、海底成像所用频率、掠射角、海底的组成与特征（包括粒径、含水量、体积密度及海底粗糙度），以及部分生物覆盖物。坚硬且粗糙的底质（如岩层出露或粗粒沉积物）通常会返回更强的信号（高散射强度，色调偏亮），而松软的底质（如细粒沉积物）则会返回较弱的信号（低散射强度，色调偏暗）。