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18 st / February 2016 www.sea-technology.com range of particle sizes. Initial results are encouraging, with observed consistency between the complementary undis- turbed measurements of particle concentration and orien- tation over spatial scales ranging from microns to tens of meters. Given that nearly all theory of light propagation in the ocean and associated simplifcations and inversion models assume random particle orientations, implications of this vertically profling enabled the same sample vol- umes to be interrogated remotely from different directions. If the particles are perfectly randomly oriented, then the remote optical assessments from different directions would be equivalent. With preferentially oriented particle felds, the optical properties, including the cross-polarized (crosspol) and co-polarized (copol) measurements, would be expected to show dependence on direc- tion of interrogation, which should be consistent with open-path optical measurement anomalies between sensors and orientation effects shown in the holo- graphic imaging. Preliminary analyses of lidar re- turned signals verifed the presence of particle scatter- ing layers, consistent with the other techniques. A second, above-water lidar was also deployed by Dr. Deric Gray and Dr. Alan Weidemann of the U.S. Naval Research Laboratory (NRL). This lidar was able to document the position of particle layers during the measurement time periods of the other sensors. Conclusion We are currently analyzing the results from the September 2015 East Sound deployment. Preferential particle orientation was found to be ubiquitous in different locations, at multiple parts of the water column, through- out the two-week sampling period. Orientation of particles consisting primarily of chain-forming or relatively large phy- toplankton was horizontal with respect to gravity and paral- lel to fow/shear streamlines. Orientation was consistent for particles with an aspect ratio greater than 2.5 over a broad T H E L E A D E R I N S U B S E A P R O P U L S I O N The Global Leader In Subsea Propulsion & Motion Control For Over 30 Years DC BRUSHLESS THRUSTERS • RS485 & Analog speed control • Full ocean depth option available • Self-contained electronics - 24 to 330VDC • Magnetically coupled propellers for reliability • Over 8,000 Tecnadyne thrusters built since 1985 Model 2020 115kgf forward 73 kgf reverse thrust www.tecnadyne.com BUILT IN THE USA At top is a graphic of scanning, profling lidar system showing two locations where 180° backscattering and attenuation are remotely sensed. Any prefer- ential particle orientation would result in different optical signals from the same sample volume when probed from different directions. At bottom are images of the hemispherical scanning lidar instru- ment and electronics housing being tested through a range of azimuthal and elevation angles.