Conductivity Temperature Depth

The deep-water observations with conductivity, temperature, depth (CTD) profilers performed in the Black Sea during the past two decades allowed one to distinguish the near-bottom mixed layer (NBML). In Fig. 3b, we present profiles of the potential temperature (T ), salinity (S), and potential density (ct ) of the Black Sea waters in the layer from 1500 to 2100 m obtained by averaging of 46 CTD profiles observed in 1985-1992 in different regions of the deep-sea area. In all three profiles shown in Fig. 3b, a distinct upper boundary of the NBML is traced at depths from 1750 to 1800 m. Above it, up to a depth of 1700 m, one finds a layer with increased vertical gradients of T , S, and a with a thickness about 100 m it separates NBML from the deep stratified layer. 

Seawater samples were collected using a rosette attached to the conductivity-temperature-depth... 

Hornbcek Pneumatic gauge from 1890. Float in stilling well from app. 1959. Differential pressure transducer — CTD (Conductivity, Temperature, Depth) — from June 2000. 

CTD Conductivity-temperature-depth (hydrographic/oceanographic bathysonde)... 

Conductivity-temperature-depth (CTD) data in the Bohai Sea show three low-temperature centers in summer in the middle and lower layers the central Bohai Straits, Liaodong Bay Mouth, and Bohai Bay Mouth. In addition, there is an evenly high-temperature center in the middle Bohai Sea. In winter the isotherms extend northwestward in the Bohai Sea with a cold tongue-shaped mass off Qinhuangdao towards the southeast, presenting a saddle-like isotherm pattern in the central Bohai Sea. 

Conductivity as a function of S, T and P Conductivity Temperature Depth profiler Equation of State of Seawater on the 1980 scale International Association for the Physical Sciences of the Ocean International Council for the Exploration of the Sea International Practical Temperature Scale of 1968 International Temperature Scale of 1990... 

Among the first instruments to measure almost continuously the three basic parameters in the water column (Hinkelmann, 1957 Brown, 1974), the one developed by Brown was termed Conductivity Temperature Depth profiler (CTD). This name now is in general use for such instruments. Additional sensors are often attached, e.g., sensors to measure dissolved oxygen and pH values (see Chapter 14), fluorescence, light attenuation, sound velocity and others. 

Constant Factor Depth Density Capacity Conductivity Temperature ... 

CTD and Data Logging. A digital CTD unit (Model 8705, Guildline Instruments Ltd., Smith Falls, Ontario, Canada) mounted on the Batfish see Figure 1) measures in situ conductivity, temperature, and depth (CTD) with accuracies of 0.01 ppt, 0.01 °C, and 1 dbar (full scale... 

Instruments in the underwater vehicle include conductivity, temperature, dissolved oxygen, depth, and irradiance sensors (Table I). In addition to these sensors, two pendula inside the electronics package provide continuous readings as to bank and climb altitudes while towing. 

The data presented are for samples collected by using a pump-profiling system designed to minimize atmospheric contamination. This pump sampler was attached at the end of a 400-m electrical cable with a conductivity, temperature, and depth device (CTD, Seabird SBE-9/11). The nylon hose was interfaced to an autoanalyzer for detailed analyses of N03 , N02 , NH4+, H4Si04, PO,3, and H2S. Discrete samples were taken for oxygen, manganese, and iron. 

Salinity-Temperature-Pressure (Depth). Conductivity, temperature and pressure data were collected using a Plessey Systems CTD with model 8400 data logger. These sensors were interrogated five times per second for values of temperature, conductivity (salinity), and pressure (depth). Data were recorded during the down-cast using a lowering rate of 30 m min". Niskin bottle samples were taken on every other cast to provide temperature and salinity calibration. Nominal precision of the salinity, temperature and depth measurments was 0.02 g kg", 0.02 °C and 0.2 m, respectively. 

Surface sediment samples were collected from Loch Sunart, a sea loch (fjord) on the NW coast of Scotland, during cruises aboard the R. V. Clupea (April 1999) and the R. V. Envoy (July 2001 and June 2002). Bottom water temperature and salinity measurements were recorded using a STD Plus 646 conductivity, temperature and depth (CTD) probe at each sample site (Table 1). No data were collected on pH and carbonate ion concentration. Two stationary Anderaa RCM-7 current meters complete with temperature and conductivity sensors and a data logger were deployed in the inner basin (56.6842°N, -5.6211°W) between 21 June 2001 and the 18 June 2002, and the main... 

Instruments, termed CTD, are available for the in situ measurements of conductivity, temperature and pressure (and derived depth). However, as temperature and pressure values change in situ, Eq. (3-4) cannot be used directly to calculate S. Additional relationships are needed to link S to the entire oceanic temperature and pressure ranges. Let... 

Currents can be measured at single-points in the water column by a propeller-type current meter (with a vane to also allow measuring directions) or by electromagnetic flowmeter (so-called ECM s or DRCM s). The instruments can also be combined with CTD s to measure conductivity, temperature and water depth (see further below). 

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