Temperature profiles from expendable bathythermograph (XBT) casts from the USCGC SHERMAN in the North Atlantic Ocean in support of the Integrated Global Ocean Services System (IGOSS) project from 15 September 1977 to 18 September 1977 (NODC Accession 7700763)

XBT data were collected from the USCGC SHERMAN in support of the Integrated Global Ocean Services System (IGOSS) project. Data were collected by the US Coast Guard (USCG) from 15 September 1977 to 18 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.

本次采集的抛弃式深海测温仪（expendable bathythermograph, XBT）数据源自美国海岸警卫队“谢尔曼”号（USCGC SHERMAN），用于支撑综合全球海洋服务系统（Integrated Global Ocean Services System, IGOSS）项目。该批数据由美国海岸警卫队（US Coast Guard, USCG）于1977年9月15日至1977年9月18日期间采集，后由国家海洋数据中心（National Oceanographic Data Center, NODC）按照NODC标准通用深海测温仪输出（Universal Bathythermograph Output, UBT）格式完成处理。完整格式说明可通过NODC官方网站www.nodc.noaa.gov/General/NODC-Archive/bt.html获取。

UBT文件格式用于存储通过XBT仪器获取的温度-深度剖面数据。标准型XBT可获取深度约450米或760米的剖面数据；搭配专用仪器时，最大测量深度可达1830米。每份观测记录均包含航次信息、观测位置、日期与时间。数据记录由若干温度-深度值对构成。与采用均匀5米间隔记录温度值的机械式深海测温仪（MBT）数据文件不同，XBT数据文件中的温度值对应非均匀深度点，这些点为以可接受精度记录温度曲线所需的最少数量“拐点”。不过在输出环节，用户可选择直接输出拐点处的温度值，或通过插值得到均匀深度步长下的温度值。