National Coral Reef Monitoring Program: Shallow water conductivity-temperature-depth (CTD) profiles for selected locations across the Hawaiian Archipelago

Near-shore shallow water Conductivity-Temperature-Depth (CTD) surveys provided in this collection were conducted at selected sites around the Hawaiian Archipelago as part of the ongoing National Coral Reef Monitoring Program (NCRMP). Shallow water CTD surveys provide vertical profiles of temperature, salinity, and turbidity providing indications for water masses and local sea water chemistry changes. These surveys are 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 (REA) and towed-diver surveys, both of which are archived separately.

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 is performed using Seabird Instrument's SeaSoft SBE Data Processing Software.

本数据集收录的近岸浅海温盐深（Conductivity-Temperature-Depth, CTD）调查数据，是作为持续推进的国家珊瑚礁监测计划（National Coral Reef Monitoring Program, NCRMP）的一部分，在夏威夷群岛周边选定站点开展的作业成果。浅海CTD调查可获取温度、盐度与浊度的垂直剖面数据，用以指示水团特征及局地海水化学变化。开展此类调查旨在表征海洋环境物理与化学属性的空间结构，该结构会影响快速生态评估（Rapid Ecological Assessments, REA）与拖曳式潜水员调查中观测到的活体珊瑚礁资源，后两类调查数据均已单独归档。

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），采用的设备为Sea-Bird Electronics公司生产的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仪（Wetlabs Inc.出品，可获取与浊度相关的光束透射率剖面）与溶解氧传感器（Sea-Bird Electronics公司生产的SBE43型，测量精度为饱和值的2%）。数据采集方式为：从小型船只以约0.5至0.75米每秒的下沉速率下放CTD设备至最大30米深度，采用剖面模式进行数据采集。数据处理使用Sea-Bird Instrument公司的SeaSoft SBE数据处理软件完成。