Continuous Profiling of Ocean Temperature Over Tens of Kilometers Using Optical Fiber Technology

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The PI plans to investigate whether long fiber optic arrays represent a viable means of measuring fluctuations in ocean temperature. There is a pressing need in the ocean sciences community to increase the space time density of ocean observations, particularly near the sea-surface, sea-floor and coastlines. Conventional arrays of discrete instruments are expensive and difficult to deploy even in an observatory setting. It now appears possible to use various forms of optical technology to produce long (1-100km) distributed arrays which sense temperature, pressure, acoustic and other signals continuously along their length. These arrays might be deployed on the sea floor, floated on the sea surface, towed behind moving vehicles or suspended from moorings. Optical array technology has been pioneered by the military and by the oil industry. Multi-kilometer temperature profiling arrays have been developed to monitor the heat distribution in oil wells and reservoirs. The PIs plan to establish a small test observatory at the end of the Scripps Institution of Oceanography pier. Optical temperature systems will be deployed from the observatory and into nearby Scripps Undersea Canyon, gaining rapid access to great depths. The idea is to run an intercomparison of competing technologies from the pier observatory. The PIs will compare prototype Raman and Bragg systems and create a purely electrical equivalent. These will be operated for an extended period to document seasonal variability of the coastal thermal structure and to support the design of a future coastal upwelling monitoring system. Broader ImpactsSuccessful development of precise distributed temperature sensing on optical fibers could have major impacts in many fields of oceanography. These will surely filter down to the level of education. In addition, the use scenarios make the case that the proposed sensor can impact our understanding of climatically-important processes in equatorial regions, which has clear societal relevance.