SANP1M.TIF - South Anacapa Passage sidescan sonar backscatter image in nearshore Benthic Habitat mapping Project S. California map Series. (UTM 10N, NAD83)

The sidescan sonar image of the nearshore seafloor (0 to 100 m water depths) of the southern Anacapa Passage area was mosaicked from data collected in 1999 and 2000. A Klein 2000 sidescan system was used for geophysical surveying. A Triton Elics Isis brand side-scan data recording system was used on the cruise. The 2000 survey was navigated with a Leica Differential Global Positioning System (DGPS) which provided a ship position with accuracy of 1-5 m in DGPS mode. At times during the cruise differential signal was interrupted. In non-differential mode, the receiver provided a position with 30-50 m accuracy. A KVH Industries Inc. azimuth digital gyro-compass provided ship headings with 0.5 degree accuracy. Navigation data were recorded using Yo-Nav (Gann, 1992). The sidescan fish was towed approximately 30 m above the seafloor. The distance of the fish behind the ship was not known during this survey and must be estimated when the data are processed in order to produce the sidescan image mosaics. The resolution of the processed data mosaics is 0.2 m. The data are presented here at a resolution of 1 m. This is one of a collection of digital files of a geographic information system of spatially referenced data related to the USGS Coastal and Marine Geology Program Nearshore Benthic Habitat Mapping Project. The sidescan data were processed using USGS MIPS sonar processing software (Chavez, 1984). See <http://walrus.wr.usgs.gov/nearshorehab> for more information about this data set.

阿纳卡帕海峡南部近岸海底（水深0至100米）的侧扫声呐图像，由1999年与2000年采集的实测数据拼接镶嵌而成。本次地球物理勘测采用Klein 2000型侧扫声呐系统，航次作业中搭载了Triton Elics Isis品牌侧扫数据记录系统。2000年的勘测作业采用徕卡差分全球定位系统（Leica Differential Global Positioning System, DGPS）进行导航，该系统在差分模式下可提供精度为1至5米的船舶位置数据。航次作业期间，差分信号偶尔会出现中断；在非差分模式下，接收机提供的位置精度为30至50米。KVH工业公司（KVH Industries Inc.）的方位数字陀螺罗经可提供精度为0.5度的船舶航向数据。导航数据通过Yo-Nav系统进行记录（Gann, 1992）。侧扫拖鱼在海底上方约30米处被拖曳，本次勘测未记录拖鱼距船尾的实际距离，因此在后期处理生成侧扫图像镶嵌图时，需对该距离进行估算。经处理后的数据镶嵌图原始分辨率为0.2米，本次公开的数据集分辨率为1米。本数据集隶属于美国地质调查局（USGS）海岸与海洋地质项目的近岸底栖生境制图项目，属于该项目空间参考地理信息系统数字文件集合的一部分。本次侧扫数据采用USGS MIPS声呐处理软件进行处理（Chavez, 1984）。如需了解该数据集的更多详情，请访问<http://walrus.wr.usgs.gov/nearshorehab>。