Electronic Digitization and Sensor Response Effects on Salinity Computation from CTD Field Measurements

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  • 1 Dept. of Oceanography, Universiy of Washington, Seattle 98195
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Abstract

Spikes are often observed in salinity profiles computed from measurements of conductivity, temperature and pressure. Many of these spikes are not real and are the result of a mismatch in the response functions of the sensors. Some of the spikes are also due to the sequential sampling technique used by most digitizers whereby the sensors are not sampled at the same time or position. We derive expressions to linearly correct for these two causes of spikes. When the corrections are applied to measurements in the North Pacific, a significant reduction in the number and size of the spikes is observed in high gradient regions such as the thermocline.

Abstract

Spikes are often observed in salinity profiles computed from measurements of conductivity, temperature and pressure. Many of these spikes are not real and are the result of a mismatch in the response functions of the sensors. Some of the spikes are also due to the sequential sampling technique used by most digitizers whereby the sensors are not sampled at the same time or position. We derive expressions to linearly correct for these two causes of spikes. When the corrections are applied to measurements in the North Pacific, a significant reduction in the number and size of the spikes is observed in high gradient regions such as the thermocline.

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