Royal Australian Navy (RAN) - CTD profiles

The Royal Australian Navy (RAN) collected vertical profiles of pressure, temperature and salinity measured by a Conductivity, Temperature and Depth (CTD) probe from RAN Hydrographic Survey cruises, between 2004 and 2016. There were 2 types of CTD used, the 'HS_CTD' used on smaller vessels which is lowered by a hand driven winch and the 'MVP200' CTD used on larger vessels and lowered by an electric winch. The CTD data is available as quality controlled netCDF files online at the AODN THREDDS server at http://thredds.aodn.org.au/thredds/ and also through a Web Map Service (WMS) at http://geoserver-123.aodn.org.au/geoserver. There are also metadata records, 1 per ship cruise, available at http://www.http://catalogue.aodn.org.au/geonetwork. The 2 CTD types are distinguished from one another by netCDF file naming or in the metadata record title element Data from the HS_CTD will have '_H' in the filename while MVP200 will have '_M'. HS_CTD The HS_CTD probe is 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. MVP200 CTD The MVP200 CTD is manufactured by Applied Microsystems Limited and is the "Micro CTD" model. This CTD type is referred to operationally as the MVP200_CTD. This CTD is fitted with a 4 electrode platinized conductivity cell, thermistor temperature sensor and a semiconductor strain gauge pressure sensor. The CTD sensors are calibrated at the manufacturer Applied Microsystems Limited on a 12-18 month schedule. The CTD temperature sensor is calibrated against 'Hart' temperature standards. The pressure sensor is calibrated using 'Budenburg Deadweight' standards. The conductivity sensor is calibrated using 'Hart' temperature standards and seawater samples of known conductivity. The CTD sensors are mounted to a fish-shape probe. The probe is controlled by an electric winch (MVP200 type). For downcasts the fish is allowed to free-fall (winch is in 'free-wheel' mode) under its own weight at about 2-3 ms-1 and then is winched back. Data is recorded in downcast and usually in upcast direction at a sampling rate of 25 Hz. The downcast data is of higher quality because sensors encounter undisturbed seawater so most data available are downcast files. This type of CTD is prone to a phenomenon called 'salinity spiking' caused by a mismatch between the response times of the temperature and conductivity sensor. Data undergoes a salinity de-spiking routine to correct for this. See the 'Data Quality - Lineage section' for further details on the salinity de-spiking process. 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. Data is then flagged with quality control flags after visual inspection and comparison to average climatology and historical CTD casts.

澳大利亚皇家海军（Royal Australian Navy, RAN）于2004年至2016年间，依托其水文测量巡航任务，采集了由电导率-温度-深度（Conductivity, Temperature and Depth, CTD）探针获取的压力、温度与盐度垂直剖面数据。本次采集共使用两类CTD设备：HS_CTD搭载于小型舰艇，由手动绞车下放；MVP200 CTD搭载于大型舰艇，由电动绞车下放。

上述CTD数据已以经过质量控制的netCDF文件形式，于澳大利亚海洋数据网络（AODN）的THREDDS服务器（http://thredds.aodn.org.au/thredds/）上线发布，同时也可通过网络地图服务（Web Map Service, WMS）地址http://geoserver-123.aodn.org.au/geoserver 获取。此外，每艘船舶单次巡航对应一条元数据记录，可在http://catalogue.aodn.org.au/geonetwork 查询。两类CTD设备可通过netCDF文件名或元数据记录的标题元素进行区分：HS_CTD对应的数据文件名中包含后缀`_H`，MVP200对应的数据文件名则包含后缀`_M`。

HS_CTD探针由法尔茅斯科学公司（Falmouth Scientific）制造，型号为“2英寸微型CTD”，作业中简称HS_CTD。该设备集成感应式电导率池、铂电阻温度计与硅压阻力传感器。其温度传感器依据ITS-90温标，通过控温水槽与标准CTD进行校准；压力传感器采用德鲁克压力校准器（Druck Pressure Calibrator）完成校准；电导率传感器则在控温水槽中，以已知电导率的海水样本为基准完成校准。HS_CTD由手动绞车收放，采样频率为1.83 Hz。数据同时记录下行与上行剖面数据，但由于下行剖面数据质量更优，公开可用数据以下行剖面为主。原始CTD压力数据因绞车与船舶的瞬态升降运动，未必呈现单调递增特性，因此需先对原始压力数据进行子集截取，生成单调递增序列，再通过线性插值将数据统一至1分巴（decibar）的压力间隔，并转换为netCDF格式文件。后续还将通过目视检查、与平均气候态数据及历史CTD剖面对比，为数据添加质量控制标记。

MVP200 CTD由应用微系统有限公司（Applied Microsystems Limited）制造，型号为“微型CTD”，作业中简称MVP200_CTD。该设备搭载四电极镀铂电导率池、热敏电阻温度传感器与半导体应变片式压力传感器。其传感器由制造商应用微系统有限公司按照12至18个月的周期进行校准：温度传感器以“哈特”温度标准（Hart temperature standards）为基准校准；压力传感器采用“巴登伯格静重”标准（Budenburg Deadweight standards）完成校准；电导率传感器则结合“哈特”温度标准与已知电导率的海水样本完成校准。该CTD传感器集成于鱼形探头上，由电动绞车（MVP200型）控制收放。下行剖面时，探头依靠自身重量以约2~3 m·s⁻¹的速度自由下落（绞车处于“自由轮”模式），上行时则通过绞车收回。采样频率为25 Hz，数据同时记录下行与上行剖面，其中下行剖面因传感器接触未受扰动的海水，质量更优，因此公开可用数据以下行剖面为主。该类型CTD易出现“盐度尖峰”现象，由温度与电导率传感器响应时间不匹配引发，因此需通过盐度去尖峰处理流程进行校正，相关细节可参阅“数据质量-溯源”章节。与HS_CTD类似，原始压力数据因绞车与船舶的瞬态运动未必单调，需先截取生成单调递增序列，再通过线性插值统一至1分巴压力间隔，最后通过目视检查、与气候态及历史CTD剖面对比，添加质量控制标记。