Advances in measuring ocean salinity with an optical sensor

Abstract

Absolute salinity measurement of seawater has become a key issue in thermodynamic models of the oceans. One of the most direct ways is to measure the seawater refractive index which is related to density and can therefore be related to the absolute salinity. Recent advances in high resolution position sensitive devices enable us to take advantage of small beam deviation measurements using refractometers. This paper assesses the advantages of such technology with respect to the current state-of-the-art technology. In particular, we present the resolution dependence on refractive index variations and derive the limits of such a solution for designing seawater sensors well suited for coastal and deep-sea applications. Particular attention has been paid to investigate the impact of environmental parameters, such as temperature and pressure, on an optical sensor, and ways to mitigate or compensate them have been suggested here. The sensor has been successfully tested in a pressure tank and in open oceans 2000 m deep.

Kinetic models of peroxidase activity in potato leaves infected with late blight based on hyperspectral data

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Une avancée optique pour la mesure de la salinité absolue des océans

“…L'étalonnage, effectué au SHOM, a permis d'évaluer la correction à apporter à la position du laser mesurée sur le PSD en fonction de la température, la pression Une première mondiale lors de la campagne PROTEVS Le prototype étant prêt pour des essais in situ, ceux-ci ont été réalisés au printemps 2010, par le SHOM, lors de la campagne océanographique PROTEVS-2010 à bord du Pourquoi Pas [3] (figure 3).…”

New Equations for Sea Water Density Calculation Based on Measurements of the Sound Speed

“…The traditional laboratory chemical analysis of sea water with sampling from various depths is a long, time-consuming, complex, and costly process. Therefore, salinity is usually determined indirectly through the results of measuring of any physical index of seawater, for example, based on the electric conductivity of the sea water or the sea water refractive index [2]. Between salinity and conductivity a functional relationship is established with a reasonable accuracy.…”