NSFGEO-NERC: Direct comparison of ocean temperature and velocity structure from in-situ measurements and distributed optical fiber sensing

Despite the many significant leaps in understanding brought about by technological progress in ocean observations, a crucial blind spot remains in our ocean observing capabilities: currently, no established approach exists to robustly measure the ocean interior at horizontal resolutions of O(10-100 m) over any meaningful spatio-temporal scales, e.g., continuous horizontal distances of many kms over times of weeks to years. This gap has limited our understanding of a breadth of oceanic processes operating on those scales, and has prevented testing of new theoretical concepts or model-based predictions of the dynamics and large-scale impacts of such processes. Important oceanic phenomena lying within the above observational blind spot permeate almost every topical problem in physical oceanography and marine biogeochemistry. Measurement by moored or autonomous systems is either highly restricted in space (for moorings) or heavily aliased in both space and time (for autonomous systems). Unlocking progress in tackling these (and many related) problems thus requires a new way of observing the ocean - one that enables concurrent resolution of fine horizontal and vertical scales with a spatio-temporal outreach that is sufficiently extensive to sample many events of the target phenomenon. This project investigates a new, low-cost, and environmentally friendly passive approach to remote sensing of the ocean, which takes advantage of the ambient random wave motion (noise) and the ability to quantitatively characterize this motion with high spatial and temporal resolution using distributed optical fibre sensing within legacy seafloor infrastructure of power and telecommunication cables.
In a wide range of frequencies spanning from below 1 mHz to hundreds of kHz and encompassing acoustic and gravity waves, ocean waves create pressure fluctuations, which can be harnessed to interrogate the ocean and measure physical parameters of the water column, ice cover, and the seabed. By...