BackscatterA [USGS SWATH]--Monterey Canyon and Vicinity, California

This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate grids depending on mapping system and processing method. These metadata describe acoustic-backscatter data collected and processed by the U.S. Geological Survey. The raster data files are included in "BackscatterA_USGS_SWATH_MontereyCanyon.zip," which is accessible from http://dx.doi.org/10.5066/F7XD0ZQ4.
The acoustic-backscatter map of Monterey Canyon and Vicinity, California, were generated from acoustic-backscatter data collected by the U.S. Geological Survey (USGS), by Monterey Bay Aquarium Research Institute (MBARI), and by California State University, Monterey Bay (CSUMB). Mapping for the entire map area was completed between 1998 and 2014 using a combination of 30-kHz Simrad EM-300 and 200-kHz/400-kHz Reson 7125 multibeam echosounders, as well as 234-kHz and 468-kHz SEA SWATHplus bathymetric sidescan-sonar systems. The USGS mapping was completed in 2009 and 2014. 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DS 781数据集部分提供加利福尼亚州蒙特雷峡谷及周边区域的声散射（acoustic-backscatter）地图数据。声散射数据根据测绘系统与处理方法的不同，以独立网格文件形式提供。本元数据用于说明由美国地质调查局（U.S. Geological Survey, USGS）采集并处理的声散射数据。栅格数据文件打包于"BackscatterA_USGS_SWATH_MontereyCanyon.zip"，可通过http://dx.doi.org/10.5066/F7XD0ZQ4获取。

加利福尼亚州蒙特雷峡谷及周边区域的声散射地图，由美国地质调查局（USGS）、蒙特雷湾水族馆研究所（Monterey Bay Aquarium Research Institute, MBARI）以及加州州立大学蒙特雷湾分校（California State University, Monterey Bay, CSUMB）采集的声散射数据绘制而成。整个测绘区域的制图工作于1998年至2014年间完成，采用了30 kHz Simrad EM-300、200 kHz/400 kHz Reson 7125多波束测深仪，以及234 kHz与468 kHz SEA SWATHplus测深侧扫声呐系统的组合方案。其中美国地质调查局的测绘工作分别于2009年和2014年完成。在最终成像图中，色调越亮代表声散射强度越高，色调越暗则代表声散射强度越低。声散射强度是声波脉冲与海底、以及浅地表内部特性之间复杂相互作用的结果，可大致反映海底的质地与组成特征。声散射强度受多方面因素影响：声波源级、海底成像所用频率、掠射角、海底组成与特性（包括粒度、含水量、体积密度及海底粗糙度），以及部分生物覆盖物。质地坚硬且粗糙的海底类型（如岩石露头或粗粒沉积物）通常会产生更强的散射强度（高声散射，对应亮色调），而质地柔软的海底类型（如细粒沉积物）则会产生较弱的散射强度（低声散射，对应暗色调）。