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) from 21 September 1977 to 23 September 1977 (NODC Accession 7700760)

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 from 21 September 1977 to 23 September 1977. 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.

本数据集的投弃式温深仪（expendable bathythermograph，XBT）数据采集自美国海岸警卫队ACUSHNET号舰艇，为支撑综合全球海洋服务系统（Integrated Global Ocean Services System，IGOSS）的相关工作而采集。该数据由美国海岸警卫队于1977年9月21日至1977年9月23日期间采集完成，后由美国国家海洋数据中心（NODC）按照其制定的通用温深仪输出（Universal Bathythermograph Output，UBT）标准格式进行处理。完整的格式说明可从NODC官网获取，网址为www.nodc.noaa.gov/General/NODC-Archive/bt.html。

UBT文件格式用于存储通过投弃式温深仪采集的温度-深度剖面数据。标准型投弃式温深仪可获取深度约450米或760米的剖面数据；若配备专用仪器，测量深度可达1830米。每份观测记录均包含航次信息、观测位置、日期与时间。数据记录由多组温度-深度值对构成。与MBT数据文件不同——后者的温度值以固定5米间隔记录，XBT数据文件中的温度值对应非均匀分布的深度。这些深度点为以可接受精度记录温度曲线所需的最少数量的“拐点”。不过在输出环节，用户可选择按拐点输出温度值，或通过插值得到均匀深度间隔下的温度值。