OCEANOGRAPHIC MEASUREMENTS

The following boxes present four case studies to illustrate how the introduction of reference materials has decreased the uncertainty of the chemical oceanographic measurement of salinity (Box 2.1), DOC (Box 2.2), and dissolved inorganic carbon (DIC) (Box 2.3). Box 2.4 illustrates the acute need for pigment reference materials, which are currently unavailable. 

The greatest impact of the Clark oxygen electrodes has been in medicine and physiology. (A schematic diagram of a catheter-size Clark electrode is shown in Fig. 7.7.) On the other hand, a temperature- and pressure-compensated Clark electrode for oceanographic measurements up to 600 ft has also been developed (Fatt, 1976). The normal temperature coefficient of the Clark electrode is 2%/°C... 

During the cruises in the 1950s and 1960s, oceanographic measurements were performed by means of reversing thermometers (Wolf, 1959) and Nansen bottles. Since 1974, the seawater was collected in a rosette of tube samplers combined with the CTD (Voigt et al., 1976 Seehase, 1980). Between 1951 and 1960/1961, currents were measured by means of Ekman-Merz current meters (Helm, 1968). 

During the 1950s, the proprietary development of oceanographic measuring instruments was pushed owing to the lacking availability of suitable equipment. Since 1961, first... 

Another item of the forthcoming recommendation by the WG127 concerns a new salinity definition called Reference-Composition Salinity, bringing this fundamental oceanographic measure back into the interdisciplinary scientific and engineering family of the SI system of units (BIPM, 2006 Millero et al., 2008). The chemical Reference Composition is given in Table 20.1. On the basis of this definition, the recommended conversion formula between Absolute Salinity, S, and Practical Sahnity, S, of standard seawater is given by... 

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