Dissolved oxygen concentration is determined with a submersible electrode which produces an electrical current proportional to the amount of oxygen dissolved in the water. The electrode is calibrated each sampling date using discrete water samples . The discrete samples are analyzed using the high-precision Winkler titration, a standard technique of oceanographers. This plot shows the agreement between the measured (Winkler) dissolved oxygen and the calculated (electrode) dissolved oxygen. The points on this plot represent all the measurements made in South Bay during 1996. The average deviation between calculated oxygen and measured oxygen is 0.16 milligrams per liter, equivalent to a mean error of 2%.

See examples of dissolved oxygen vertical profiles.