ADCP current velocity data for CTD stations of the BROKE-West voyage of the Aurora Australis, 2006

The Acoustic Doppler Current Profiler (ADCP) data were acquired constantly over the duration of the Australian 2006 V3 BROKE-West survey. Data presented here are the results of 1/2 hour integrations of the cruise data from the start of the voyage in Fremantle, Australia, to the start of the return leg just north of Australia's Davis Station in Antarctica (-66.56S, 77.98E). North and eastward components of the current velocity are given for depths up to 300m below the surface along the ship track.

Data Acquisition:

The shipboard ADCP is a continuous broadband recording device that operates over the duration of the voyage, ensonifying the water column once a second. As the instrument is fixed to the ship, it has a range of approximately 250m deep. Data from the shipboard Ashtek 3 dimensional GPS system is used along with bottom tracking data (when the water is shallow enough i.e. less than 250m) and automatically integrated into ADCP ping data to provide absolute current velocities.

Data Processing:

The ship ADCP constantly and automatically collects and stores raw .rawdp binary files in ensembles of three minutes worth of pings. This is regularly automatically collated into larger .adp files containing data for several hours (200+ ensembles). This data are processed for use in analysis using specialist software provided by Mark Rosenberg (mark.rosenberg AT utas.edu.au) that integrates together data from the ADCP .adp files for periods (30 minutes in this case) over a give time (from cruise start to the 3-Mar-2006). This produces .any ASCII files. These ASCII files are read into the Matlab processing package using scripts provided by Sergeui Sokolov (sergeui.sokolov AT csiro.au) which then produces the .mat matlab data files covered by this metadata. ADCP data requires proper calibration with respect to ship motion, which were not carried out for this data set, and could cause significant change when processed properly after the voyage.

Dataset format:

The processed ADCP file is given in matlab .mat format. All 1/2 hour integrations of ADCP data for BROKE-West from 3 days (31-dec-2005) before departure from Fremantle, to the 3-Mar-2006 are included, each column in each matrix or array representing an individual 1/2 hour integration in chronological order. There are numerous gaps in the data that occurred when the ADCP crashed and was not immediately reset or when bad data prevented processing. The location can be identified by plotting a scatter plot of longitude vs latitude, and the times by plotting the julian date.

The matlab variables contained in the BROKE_West_ADCP.mat file are contained inside the adcp structure:

lon: Longitude (decimal degrees)
lat: Latitude (decimal degrees)
time: Each column gives the year month day and hour of collection of the corresponding columns in the other variables.
depth: Depth of each corresponding velocity value for each 1/2 profile. 60 fixed bin depths are given for each profile. (meters)
press: As for depth but given in db. (db)
u: Absolute current eastward component in ms-1 for each depth and profile.
v: Absolute current northward component in ms-1 for each depth and profile.
unav: Ship absolute eastward component in ms-1 for each profile
vnav: Ship absolute northward component in ms-1 for each profile
jtime: Julian date for each profile (julian days)
badvals: Indexes of anomolous latitude and longitude values

Acronyms used:

ADCP: Accoustic Doppler Current Profiler
IASOS: Institute of Antarctic and Southern Ocean Studies
CSIRO: Commonwealth Scientific and Industrial Research Organisation

This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).

声学多普勒流速剖面仪（Acoustic Doppler Current Profiler, ADCP）数据在澳大利亚2006年V3 BROKE-West科考航次全程持续采集。本次发布的数据为该航次从澳大利亚弗里曼特尔起航，至南极澳大利亚戴维斯站北侧（南纬66.56°，东经77.98°）返航段起始处的整段巡航数据的半小时积分结果。沿船舶航行轨迹，提供了表层下至300米深度范围内的海流北向与东向分量。

数据采集：
船载ADCP为连续宽带记录设备，在航次全程运行，每秒对水体剖面进行一次声束照射。由于该仪器固定于船体之上，其有效探测深度约为250米。本数据集采用船载Ashtek三维GPS系统数据，结合底跟踪数据（仅适用于水深小于250米的浅水区），并自动整合至ADCP ping数据中，从而计算得到绝对海流速度。

数据处理：
船载ADCP持续自动采集并存储原始.rawdp二进制文件，以每3分钟的ping数据组为单位进行存储。这些文件会被定期自动整合为更大的.adp文件，单文件包含数小时的数据（200余个数据组）。本数据集采用Mark Rosenberg（mark.rosenberg AT utas.edu.au）提供的专业软件进行分析处理，该软件可将ADCP .adp文件中的数据按指定时段（本案例中为30分钟）进行整合，整合时段范围为航次起航至2006年3月3日。该流程会生成.any格式的ASCII文件。随后采用Sergeui Sokolov（sergeui.sokolov AT csiro.au）提供的脚本，将这些ASCII文件导入Matlab处理工具包，最终生成本元数据所涵盖的.mat格式Matlab数据文件。ADCP数据需针对船体运动进行恰当的校准，但本数据集未完成该步骤；若在航次结束后进行规范化处理，校准操作可能会对结果产生显著影响。

数据集格式：
处理后的ADCP数据以Matlab .mat格式存储。本数据集涵盖了BROKE-West航次从弗里曼特尔起航前3天（2005年12月31日）至2006年3月3日期间所有半小时积分时段的ADCP数据，每个矩阵或数组中的每一列均代表按时间顺序排列的单个半小时积分时段数据。数据中存在多处缺失，其成因包括ADCP宕机未及时复位，以及无效数据导致处理中断。可通过绘制经度-纬度散点图确定采样位置，通过绘制儒略日图确定采样时间。

BROKE_West_ADCP.mat文件中的Matlab变量均存储于adcp结构体中：
lon：经度（十进制度）
lat：纬度（十进制度）
time：每一列对应其他变量中同列采样数据的采集年、月、日及时刻
depth：每个半小时剖面中各流速值对应的深度，每个剖面包含60个固定分层深度（单位：米）
press：与depth含义一致，但以分贝（db）为单位
u：各深度、各剖面对应的绝对海流东向分量，单位：米每秒（ms⁻¹）
v：各深度、各剖面对应的绝对海流北向分量，单位：米每秒（ms⁻¹）
unav：每个剖面对应的船体绝对东向速度，单位：米每秒（ms⁻¹）
vnav：每个剖面对应的船体绝对北向速度，单位：米每秒（ms⁻¹）
jtime：每个剖面对应的儒略日（儒略天数）
badvals：异常经纬度值的索引

所用缩略词：
ADCP：声学多普勒流速剖面仪
IASOS：南极与南大洋研究所
CSIRO：澳大利亚联邦科学与工业研究组织

本工作为ASAC项目2655与2679（ASAC_2655、ASAC_2679）的研究成果。