National Coral Reef Monitoring Program: Shallow Water Conductivity-Temperature-Depth (CTD) Profiles for selected locations across the Northwestern Hawaiian Islands from 2015-07-31 to 2015-08-19 (NCEI Accession 0161170)

Near-shore shallow water Conductivity-Temperature-Depth (CTD) surveys provided vertical profiles of temperature, salinity, and turbidity providing indications for water masses and local sea water chemistry changes. These surveys were conducted to characterize the spatial structure of the physical and chemical properties of the ocean environment influencing the living coral reef resources observed during Rapid Ecological Assessments and towed-diver surveys. Water samples were collected at the shallow water CTD sites to examine near-shore water quality. Shallow CTD casts are vertical profiles (max 30 meter depth, downcast only) of water column conductivity, temperature, and pressure (Sea-Bird Electronics, SBE19-plus; accuracy of 0.005 S m-1 in conductivity, 0.0002C in temperature, and 0.1% in pressure). A transmissometer (Wetlabs Inc; provides profiles of beam transmittance, related to turbidity) and a dissolved oxygen sensor (Sea-Bird Electronics, SBE43; accuracy of 2% of saturation) are also attached. Data are collected by lowering the CTD in a profiling mode from a small boat at a descent rate of approximately 0.5 to 0.75m s-1 to a maximum depth of 30m. Data processing was performed using Seabird Instrument's SeaSoft SBE Data Processing Software (http://www.seabird.com/software/SBEDataProcforWindows.htm).

近岸浅海电导率-温度-深度（Conductivity-Temperature-Depth, CTD）调查获取了温度、盐度与浊度的垂直剖面数据，可为水团特征及局地海水化学变化提供指示依据。本次调查旨在刻画海洋环境物理与化学属性的空间分布格局，该属性会对快速生态评估（Rapid Ecological Assessments）与拖曳式潜水调查中观测到的活体珊瑚礁资源产生影响。研究人员在浅海CTD站位采集水样，以监测近岸海水水质状况。浅海CTD剖面为水柱电导率、温度与压力的垂直剖面（最大深度30米，仅包含下行剖面），所用设备为Sea-Bird Electronics公司的SBE19-plus型仪器，其电导率测量精度为0.005 S·m⁻¹，温度测量精度为0.0002℃，压力测量精度为0.1%。该系统还搭载了透射率计（Wetlabs Inc，可获取与浊度相关的光束透射率剖面数据）以及溶解氧传感器（Sea-Bird Electronics公司的SBE43型，测量精度为饱和度的2%）。数据采集方式为：从小型船舶上以剖面模式下放CTD设备，下放速度约为0.5至0.75米每秒，最大下放深度达30米。数据处理采用Seabird Instrument公司的SeaSoft SBE数据处理软件完成，软件访问地址为http://www.seabird.com/software/SBEDataProcforWindows.htm。