RAN CTD Profile Data - SMB DUYFKEN ProjectID: HI446(C)DUY_H From: 2009-02-12 To: 2009-02-23

This dataset contains quality controlled vertical profiles of pressure, temperature and salinity measured by a Conductivity, Temperature and Depth (CTD) probe. The dataset contains 11 CTD profiles (casts) obtained during RAN Hydrographic Survey cruise HI446(C)DUY_H from SMB DUYFKEN.

The CTD was manufactured by Falmouth Scientific and is the "2-inch Micro CTD" model. This CTD type is referred to operationally as the HS_CTD. This CTD is fitted within an inductive type conductivity cell, a platinum thermometer and silicon pressure sensor.

The CTD temperature sensor is calibrated on the ITS-90 temperature scale against a master CTD using a controlled temperature bath. The pressure sensor is calibrated using a Druck Pressure Calibrator. The conductivity sensor is calibrated in a temperature controlled bath against seawater samples of known conductivity.

The HS_CTD is lowered and raised by a hand winch sampling at a rate of 1.83 Hz. Data files were recorded in the downcast and upcast direction but most data is from downcasts due to higher quality. Raw CTD pressure data is not always monotonic due to transient up/down motion of winch/ship. Raw pressure data is subsetted to give a monotonic (increasing) sequence and then linearly interpolated to 1 decibar pressure intervals and converted to netCDF format files. Data is then flagged with quality control flags after visual inspection and comparison to average climatology and historical CTD casts.

本数据集包含经质量管控的压力、温度与盐度垂直剖面数据，由电导率-温度-深度（Conductivity, Temperature and Depth, CTD）探针采集得到。本数据集共包含11组CTD剖面（casts），采集自RAN水文调查航次HI446(C)DUY_H，数据由SMB DUYFKEN号科考船获取。

该CTD由Falmouth Scientific公司制造，型号为"2英寸微型CTD"。该型号CTD在业务应用中被称为HS_CTD，其内置感应式电导率池、铂电阻温度计与硅基压力传感器。

该CTD的温度传感器采用恒温槽比对标准CTD的方式，按照ITS-90国际温标完成校准；压力传感器使用Druck压力校准仪进行校准；电导率传感器则在恒温槽中，通过与已知电导率的海水样品比对完成校准。

该HS_CTD通过手动绞车完成下放与回收，采样频率为1.83赫兹。数据文件同时记录下放剖面与回收剖面的数据，但由于下放剖面的数据质量更优，绝大多数有效数据均来自下放剖面。受绞车与船舶的瞬态升降运动影响，原始CTD压力数据并非始终保持单调递增。因此，原始压力数据会被截取为单调递增序列，随后通过线性插值处理至1分巴的压力间隔，并转换为netCDF格式文件。最后，经目视检查、与平均气候学数据及历史CTD测站剖面比对后，为所有数据添加质量控制标记。