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Auxiliary Hydraulic Variables
Published in Jochen Aberle, Colin D. Rennie, David M. Admiraal, Marian Muste, Experimental Hydraulics: Methods, Instrumentation, Data Processing and Management, 2017
Jochen Aberle, Colin D. Rennie, David M. Admiraal, Marian Muste
Conductivity-Temperature-Depth (CTD) probes are designed specifically to determine water density based on measurements of conductivity, temperature and pressure (see Figure 6.7.1 for an example). CTDs have been used since the 1950s by oceanographers and limnologists (Stewart, 2008). CTDs have also been used to assess mixing processes in rivers, particularly in estuaries (e.g., Kawanisi, 2004). Determination of vertical profiles of density can be achieved by lowering a continuously recording CTD throughout the water column. CTDs can also be towed to obtain longitudinal data. The translation speed and the sampling frequency determine the measurement resolution. As an example, the Seabird SBE 911 plus CTD has a sampling frequency of 24 Hz.
Experimental study on integrated and autonomous conductivity-temperature-depth (CTD) sensor applied for underwater glider
Published in Marine Georesources & Geotechnology, 2021
Bin Lv, Hai-lin Liu, Yi-fan Hu, Cheng-xuan Wu, Jie Liu, Hai-jing He, Jie Chen, Jian Yuan, Zhao-wen Zhang, Lin Cao, Hui Li
Conductivity, temperature and depth (CTD) sensors are the major tools used to determine physical properties of seawater parameters, demonstrating information about oceanic circulation, mixing and climate processes. The CTD measurement technology is vital to the study on the rapid climate change of ocean and the globe (Crescentini, Bennati, and Tartagni 2012; Murphy and Janzen 2015). Since the early 1970s, CTD sensors have been adopted as crucial hydrological survey and ecological tools, helping scientists obtain the environmental parameters of marine physics, and provide important essential parameters (e.g., temperature, salinity and depth) for the study on the environment, flow field and hydrodynamics of marine physics (Topham and Perkin 1988; Duraibabu et al. 2017). Buoyancy-driven underwater gliders have been increasingly used for marine environmental monitoring. They can go upward and downward to continuously measure and profile ocean hydrodynamic parameters by regulating the buoyancy system. Such applications often require precise instruments to sample temperature, salinity and pressure data (Schmitt and Petitt 2006; Lidtke, Turnock, and Downes 2018). Glider is a novel underwater robot combining buoys and subsurface buoy technology with conventional underwater robot technology (Liu, Weisberg, and Lembke 2015). As compared with the conventional underwater robot, it can operate in tough marine environments and exhibit the excellent advantages of low energy consumption and small dependence on the mother ship. Accordingly, gliders can be used for long-distance, large-scale and long-term marine environment measurement and monitoring, as well as mine detection and sea area monitoring (Lasheras and Mourre 2018).