Temperature profiles from expendable bathythermograph (XBT) casts from the USCGC MELLON in the North Pacific Ocean in support of the Integrated Global Ocean Services System (IGOSS) project from 21 September 1976 to 27 September 1976 (NODC Accession 7601816)

XBT data were collected from the USCGC MELLON in support of the Integrated Global Ocean Services System (IGOSS) project. Data were collected by the US Coast Guard (USCG) from 21 September 1976 to 27 September 1976. 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“梅隆”号（USCGC MELLON）科考船，旨在支撑综合全球海洋服务系统（Integrated Global Ocean Services System，IGOSS）项目。数据采集工作由美国海岸警卫队（US Coast Guard，USCG）于1976年9月21日至1976年9月27日完成，后续由国家海洋数据中心（National Oceanographic Data Center，NODC）按照其制定的通用温深仪输出（Universal Bathythermograph Output，UBT）标准格式进行标准化处理。完整的格式说明文档可通过NODC官方网站的https://www.nodc.noaa.gov/General/NODC-Archive/bt.html 查阅获取。

UBT文件格式专用于存储由投弃式温深仪（XBT）采集得到的温度-深度剖面数据。标准型XBT可获取深度约450米或760米的温度剖面，搭载专用拓展仪器时，测量深度可达1830米。每条观测记录均包含航次信息、观测位置、观测日期与时间。数据记录主体由温度-深度值对构成。与以5米均匀间隔记录温度值的机械温深仪（Mechanical Bathythermograph，MBT）数据文件不同，本XBT数据文件中的温度值对应非均匀分布的深度。这些深度点为记录温度曲线以达到可接受精度所需的最少采样点，即“拐点”。但在数据输出阶段，用户可自主选择获取拐点处的原始温度值，或通过插值计算得到均匀深度增量下的温度值。