CTD Data from the Rectangular Midwater Trawl collected during the BROKE-West voyage of the Aurora Australis, 2006

The CTD data were acquired when the RMT instrument was in the water.

Data Acquisition:

There is a FSI CTD sensor housed in a fibreglass box that is attached to the top bar of the RMT. The RMT software running in the aft control room establishes a Telnet connection to the aft control terminal server which connects to the CTD sensor using various hardware connections. Included are the calibration data for the CTD sensor that were used for the duration of the voyage.

The RMT software receives packet of CTD data and every second the most recent CTD data are written out to a data file. Additional information about the motor is also logged with the CTD data.

Data are only written to the data file when the net is in the water. The net in and out of water status is determined by the conductivity value. The net is deemed to be in the water when the conductivity averaged over a 10 second period is greater than 0. When the average value is less than 0 the net is deemed to be out of the water. New data files were automatically created for each trawl.

Data Processing:

1. Adjustment of the net open time.

If the net did not open when first attempted then the net was 'jerked' open. This meant the winch operator adjusted the winch control so that it was at maximum speed and then turned it on for a very short time. This had the effect of dropping the net a short distance very quickly. This dislodges the net hook from its cradle and the net opens. The scientist responsible for the trawl would have noted the time in the trawl log book that the winch operator turned on the winch to jerk the net.

The data files will have started the 'net open' counter 10 seconds after the user clicks the 'Net Open' button. If this time did not match the time written in the trawl log book by the scientist, then the net open time in the CSV file was adjusted. The value in the 'Net Open Time' column will increment from the time the net started to open to the time that the net started to close.

The pressure was also plotted to ensure that the time written down in the log book was correct. When the net opens there is a visible change in the CTD pressure value received. The net 'flies' up as the drag in the water increases as the net opens. If the time noted was incorrect then the scientist responsible for the log book, So Kawaguchi, was notifed of the problem and the data file was not adjusted.

2. Removing unused columns from the original log files.

The original log files that were produced by the RMT software were trimmed to remove any columns that did not pertain to the CTD data. These columns include the motor information and the ITI data. The ITI data gives information about the distance from the net to the ship but was not working for the duration of the BROKE-West voyage. This trimming was completed using a purpose built java application. This java class is part of the NOODLES source code.

Dataset Format:

The dataset is in a zip format. There is a .CSV file for each trawl, 125 in total.
There were 51 Routine trawls and 74 Target Trawls.
The file naming convention is as follows:

[Routine/Target]NNN-rmt-2006-MM-DD.csv

Where,

NNN is the trawl number from 001 to 124.
MM is the month, 01 or 02
DD is the day of the month.

Also included in the zip file are the calibration files for each of the CTD sensors and the current documentation on the RMT software.

Each CSV file contains the following columns:

Date (UTC)
Time (UTC)
Ship Latitude (decimal degrees)
Ship Longitude (decimal degrees)
Conductivity (mS/cm)
Temperature (Deg C)
Pressure (DBar)
Salinity (PSU)
Sound Velocity (m/s)
Fluorometer (ug/L chlA)
Net Open Time (mm:ss) If the net is not open this value will be 0, else the number of minutes and seconds since the net opened will be displayed.

When the user clicks the 'Net Open' button there is a delay of 10 seconds before the net starts to open. The value displayed in the 'Net Open Time' column starts incrementing once this 10 seconds delay has passed. Similarly when the user clicks the 'Net Close' button there is a delay of 6 seconds before the net starts to close. Thus the counter stops once this 6 seconds has passed.

Acronyms Used:

CTD: Conductivity, Temperature, Pressure
RMT: Rectangular Midwater Trawl
CSV: Comma seperated value
FSI: Falmouth Scientific Inc
ITI: Intelligent Trawl Interface

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

本数据集的CTD（Conductivity, Temperature, Pressure，电导率、温度、压力）数据采集于RMT（Rectangular Midwater Trawl，矩形中层拖网）设备入水期间。

数据采集流程：
安装于RMT顶部横杆的玻璃钢外壳内集成了FSI（Falmouth Scientific Inc，福尔茅斯科学公司）CTD传感器。运行于艉控制室的RMT软件会与艉部控制终端服务器建立Telnet连接，后者通过多种硬件链路与CTD传感器相连。本数据集包含本次航次全程使用的该CTD传感器的校准数据。
RMT软件会接收CTD数据报文，每秒将最新的CTD数据写入数据文件。此外，与CTD数据同步记录的还有电机的相关信息。
仅当拖网入水时，数据才会写入数据文件。拖网的入水/出水状态通过电导率值判定：若10秒周期内的平均电导率大于0，则判定拖网处于入水状态；若平均电导率小于0，则判定拖网出水。每个拖网作业都会自动生成新的数据文件。

数据处理流程：
1. 拖网开网时间校准
若首次尝试开网失败，则会通过“猛拉”动作开启拖网：具体操作为绞车操作员将绞车调速至最大档位，短暂启动绞车，使拖网快速小幅下放，从而将网钩从托架上脱开，实现拖网开网。负责拖网作业的科研人员会在拖网日志中记录绞车操作员启动绞车进行猛拉操作的时间。
RMT软件会在用户点击“开网”按钮10秒后启动“开网计时”。若该计时起始时间与科研人员在拖网日志中记录的时间不符，则需对CSV（Comma Separated Value，逗号分隔值）文件中的开网时间进行校正。“开网时间”列的数值会从拖网开始开网的时刻，递增至拖网开始关网的时刻。
同时会绘制压力变化曲线，以验证日志记录的时间是否准确：拖网开网时，接收到的CTD压力数据会出现明显变化——随着拖网张开，水中阻力增大，拖网会“上浮”。若记录的时间有误，需通知负责日志记录的科研人员So Kawaguchi，且不对数据文件进行校正。

2. 移除原始日志文件中的无效列
RMT软件生成的原始日志文件会经过修剪，移除所有与CTD数据无关的列，包括电机信息及ITI（Intelligent Trawl Interface，智能拖网接口）数据。ITI数据用于记录拖网与船舶之间的距离，但在本次BROKE-West航次中该功能无法正常工作。该修剪操作通过自研Java应用程序完成，该Java类属于NOODLES源代码的一部分。

数据集格式：
本数据集采用ZIP压缩格式，包含125个拖网作业对应的CSV文件，其中常规拖网51次、目标拖网74次。
文件命名规则如下：
[Routine/Target]NNN-rmt-2006-MM-DD.csv
其中：
NNN为拖网编号，范围001至124；
MM为月份，取值01或02；
DD为当月日期。
压缩包中还包含各CTD传感器的校准文件，以及RMT软件的当前版本文档。
每个CSV文件包含以下列：
- 日期（UTC）
- 时间（UTC）
- 船舶纬度（十进制度）
- 船舶经度（十进制度）
- 电导率（mS/cm）
- 温度（℃）
- 压力（dBar）
- 盐度（PSU）
- 声速（m/s）
- 荧光计（μg/L chlA）
- 开网时间（mm:ss）：若拖网未张开，则该值为0；否则显示自拖网开网以来的分钟数与秒数。
用户点击“开网”按钮后，会有10秒的延迟，拖网才会开始开网，“开网时间”列的数值会在该10秒延迟结束后开始递增。同理，点击“关网”按钮后，会有6秒的延迟，拖网才会开始关网，计时会在该6秒延迟结束后停止。

缩写说明：
CTD：电导率、温度、压力（Conductivity, Temperature, Pressure）
RMT：矩形中层拖网（Rectangular Midwater Trawl）
CSV：逗号分隔值（Comma Separated Value）
FSI：福尔茅斯科学公司（Falmouth Scientific Inc）
ITI：智能拖网接口（Intelligent Trawl Interface）

本工作作为ASAC项目2655与2679（ASAC_2655、ASAC_2679）的一部分完成。