Temperature profiles from expendable bathythermograph (XBT) casts from the USCGC ACUSHNET in the North Atlantic Ocean in support of the Integrated Global Ocean Services System (IGOSS) on 21 November 1975 (NODC Accession 7501199)

XBT data were collected from the USCGC ACUSHNET in support of the Integrated Global Ocean Services System (IGOSS). Data were collected by the US Coast Guard on 21 November 1975. Data were processed by NODC to the NODC standard Universal Bathythermograph Output (UBT) format. Full format description is available from NODC at www.nodc.noaa.gov/General/NODC-Archive/bt.html.

The UBT file format is used for temperature-depth profile data obtained using expendable bathythermograph (XBT) instruments. Standard XBTs can obtain profiles at depths of about 450 or 760 m. With special instruments, measurements can be obtained to 1830 m. Cruise information, position, date, and time are reported for each observation. The data record comprises pairs of temperature-depth values. Unlike the MBT data file, in which temperature values are recorded at uniform 5m intervals, the XBT Data File contains temperature values at non-uniform depths. These depths are at a minimum number of points ("inflection points") required to record the temperature curve to an acceptable degree of accuracy. On output, however, the user may request temperature values either at inflection points or interpolated to uniform depth increments.

本数据集的XBT数据采集自美国海岸警卫队"ACUSHNET"号，用于支撑综合全球海洋服务系统（Integrated Global Ocean Services System, IGOSS）。该数据由美国海岸警卫队于1975年11月21日采集，后由美国国家海洋数据中心（National Oceanographic Data Center, NODC）按照NODC标准的通用深海温度剖面仪输出（Universal Bathythermograph Output, UBT）格式进行标准化处理。完整的格式说明可通过NODC官网获取，网址为www.nodc.noaa.gov/General/NODC-Archive/bt.html。

UBT文件格式用于记录使用投放式深海温度剖面仪（expendable bathythermograph, XBT）仪器获取的温度-深度剖面数据。标准XBT可获取约450米或760米深度的剖面数据；配备专用仪器时，测量深度可达1830米。每份观测数据均包含航次信息、观测位置、日期与时间。数据记录由温度-深度值对组成。与机械式深海温度剖面仪（Mechanical Bathythermograph, MBT）数据文件不同——MBT数据文件以均匀5米间隔记录温度值——XBT数据文件中的温度值对应的采样深度并不均匀，其采样深度仅选取最少数量的"拐点"，以可接受的精度完整记录温度曲线。不过在数据输出环节，用户可选择获取拐点处的原始温度值，或通过插值得到均匀深度增量下的温度值。