Contours--Offshore Santa Cruz, California

This part of DS 781 presents data for the bathymetric contours for several seafloor maps of the Offshore Santa Cruz map area, California. The vector data file is included in "Contours_OffshoreSantaCruz.zip", which is accessible from http://dx.doi.org/10.5066/F7TM785G. 10-m interval contours of the Offshore Santa Cruz map area, California, were generated from bathymetry data collected by the U.S. Geological Survey (USGS). Mapping was completed in 2009 using a 234-kHz SWATHplus bathymetric sidescan-sonar system. The mapping mission collected bathymetry data from about the 10-m isobath to beyond the 3-nautical-mile limit of California’s State Waters. Bathymetric contours at 10-m intervals were generated from a modified 2-m bathymetric surface. The original surface was smoothed using the Focal Mean tool in ArcGIS and a circular neighborhood with a radius of 20 to 30 meters (depending on the area). The contours were generated from this smoothed surface using the ArcGIS Spatial Analyst Contour tool. The most continuous contour segments were preserved while smaller segments and isolated island polygons were excluded from the final output. The contours were then clipped to the boundary of the map area.本数据集DS 781的此部分提供了加利福尼亚州圣克鲁斯近海区域多张海底地形图的海底等深线（bathymetric contours）数据。矢量数据文件存储于"Contours_OffshoreSantaCruz.zip"压缩包中，可通过链接http://dx.doi.org/10.5066/F7TM785G获取。 加利福尼亚州圣克鲁斯近海区域的10米间隔海底等深线，由美国地质调查局（U.S. Geological Survey, USGS）采集的水深数据生成。该测绘工作于2009年完成，使用的是234kHz的SWATHplus多波束测深侧扫声呐系统。此次测绘任务采集的水深数据覆盖范围约从10米等深线（isobath）延伸至加利福尼亚州州属海域3海里界限以外区域。 本次10米间隔的海底等深线基于经修正的2米分辨率水深表面模型生成。原始表面模型通过ArcGIS中的焦点均值工具（Focal Mean tool），以半径20至30米的圆形邻域（依具体区域调整半径大小）进行平滑处理。随后使用ArcGIS空间分析（ArcGIS Spatial Analyst）模块的等深线生成工具，从该平滑后的表面模型生成海底等深线。最终输出结果保留了连续性最优的等深线线段，剔除了零散线段及孤立的岛屿多边形要素。最后将生成的等深线裁剪至地图区域的边界范围内。