Temperature profiles from expendable bathythermograph (XBT) casts from the VIRGINIA KEY in the Gulf of Mexico in support of the Integrated Global Ocean Services System (IGOSS) project from 18 November 1977 to 01 December 1977 (NODC Accession 7800094)

XBT data were collected from the VIRGINIA KEY in support of the Integrated Global Ocean Services System (IGOSS) project. Data were collected by the Atlantic Oceanographic Meteorological Laboratory (AOML) from 18 November 1977 to 01 December 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）数据采集自弗吉尼亚礁（VIRGINIA KEY），服务于全球海洋综合服务系统（Integrated Global Ocean Services System，IGOSS）项目。数据由大西洋海洋气象实验室（Atlantic Oceanographic Meteorological Laboratory，AOML）于1977年11月18日至1977年12月1日采集完成。数据经国家海洋数据中心（National Oceanographic Data Center，NODC）处理，符合NODC标准通用温深仪输出（Universal Bathythermograph Output，UBT）格式。完整格式说明可通过NODC官网www.nodc.noaa.gov/General/NODC-Archive/bt.html获取。

UBT文件格式用于记录通过投弃式温深仪（XBT）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米的温度剖面数据；搭载专用仪器时，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。数据记录由温度-深度值对构成。与机械温深仪（Mechanical Bathythermograph，MBT）数据文件不同，后者的温度值按固定5米间隔记录，而XBT数据文件中的温度值对应非均匀深度。这些深度点为将温度曲线记录至可接受精度所需的最少拐点（inflection points）数量。不过在数据输出时，用户可选择按拐点输出温度值，或通过插值生成均匀深度步长下的温度值。