Backscatter [7125]-- Offshore of Monterey Map Area, California

This part of DS 781 presents 2-m-resolution Reson 7125 data for the acoustic-backscatter map of Offshore of Monterey map area, California. These metadata describe acoustic-backscatter data collected and processed by California State University, Monterey Bay (CSUMB), Seafloor Mapping Lab and processed into a map sheet by the U.S. Geological Survey. The raster data files are included in "Backscatter_7125_Monterey.zip," which is accessible from http://dx.doi.org/10.5066/F7F47M6T.
This 2-m-resolution Reson 7125 acoustic backscatter map of Offshore of Monterey map area, California, was generated from backscatter data collected by California State University, Monterey Bay (CSUMB) using a 200-kHz/400-kHz Reson 7125 multibeam echosounder. 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).
Reference Cited: California State University, Monterey Bay Seafloor Mapping Laboratory Data Library, 2015. Available at http://seafloor.otterlabs.org/SFMLwebDATA.htm (last accessed February 2016

本DS 781数据集包含加利福尼亚州蒙特雷湾外海域制图区的声后向散射（acoustic-backscatter）图所用的2米分辨率Reson 7125数据。本元数据描述了由加利福尼亚州立大学蒙特雷湾分校（CSUMB）海底制图实验室采集并处理的声后向散射数据，以及由美国地质调查局将其整饰为正式图件的过程。栅格数据文件包含于"Backscatter_7125_Monterey.zip"压缩包中，可通过http://dx.doi.org/10.5066/F7F47M6T获取。本加利福尼亚州蒙特雷湾外海域制图区的2米分辨率Reson 7125声后向散射图，由加利福尼亚州立大学蒙特雷湾分校（CSUMB）使用200kHz/400kHz Reson 7125多波束测深仪（multibeam echosounder）采集的后向散射数据生成。在最终成像成果中，色调越亮代表后向散射强度越高，色调越暗代表后向散射强度越低。后向散射强度反映了声脉冲与海底及浅表层沉积物特性之间的复杂相互作用，可用于指示海底的纹理与组分特征。后向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、海底组分与特性（包括粒径、含水量、体积密度及海底粗糙度）以及部分生物覆盖层。坚硬且粗糙的海底类型（如岩层出露区或粗粒沉积物）通常会产生更强的散射强度（高后向散射，亮色调），而松软的海底类型（如细粒沉积物）则产生较弱的散射强度（低后向散射，暗色调）。参考文献：加利福尼亚州立大学蒙特雷湾分校海底制图实验室数据文库，2015年。可通过http://seafloor.otterlabs.org/SFMLwebDATA.htm获取（最后访问时间：2016年2月）